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Past Questions
When an open-pit mine reaches to its ultimate pit limit, the locked-up coal is extracted by:
A)
Punch longwall mining
B)
Highwall mining
C)
Augur mining
D)
Hydraulic mining
Step-by-step reasoning: 1. Understanding the Scenario: When an open-pit mine reaches its 'ultimate pit limit', it means that stripping any more overburden to reach the coal would be economically unviable (the cost of removing waste exceeds the value of the coal). However, there is still coal remaining in the seam extending horizontally from the pit wall. 2. Analyzing Highwall Mining: Highwall mining is a specialized technique used specifically for this scenario. It involves using a remotely operated cutter/borer from the surface (the top of the highwall) to extract coal from the exposed face of the pit without removing the remaining overburden. 3. Evaluating other options: (a) Punch longwall mining is an underground mining method used for thin seams, not specifically for recovering coal from an open-pit limit. (c) Augur mining is similar to highwall mining but typically refers to drilling holes from the surface into a seam that is not necessarily exposed by a pit wall (often used for recovery in abandoned mines). (d) Hydraulic mining involves using high-pressure water jets to dislodge material, which is not the standard method for extracting locked-up coal at a pit limit. Therefore, Highwall mining is the most accurate technical term for recovering coal from the face of an ultimate pit limit.
Filling up of mined area in Opencast mines is known as:
A)
OB removal
B)
Trenching
C)
Reclamation
D)
Salvaging
Step-by-step reasoning: 1. The question asks for the term used when a mined-out area in an opencast (open-pit) mine is filled back in. 2. 'Reclamation' is the process of restoring land that has been mined to a natural or economically usable state. This typically involves backfilling the void with overburden (OB) and topsoil, followed by revegetation. 3. Analyzing other options: (a) 'OB removal' is the initial process of removing waste rock to access the mineral, not filling it back. (b) 'Trenching' refers to digging narrow channels, usually for drainage or utility installation. (d) 'Salvaging' refers to the recovery of useful materials or topsoil before mining begins to be used later during reclamation. Therefore, 'Reclamation' is the only term that describes the filling and restoration of the mined area.
The fall which takes place soon after withdrawal of supports is called:
A)
Local fall
B)
Main fall
C)
Air blast
D)
Rock burst
In the context of underground mining and roof support systems, a 'Local fall' refers to the immediate detachment and falling of small pieces of rock or loose strata that occurs shortly after the supports (such as timber or hydraulic props) are withdrawn or shifted. This is typically caused by the redistribution of stress in the immediate roof.
Why other options are incorrect:
- b. Main fall: This refers to the larger, systemic collapse of the roof (goaf) that occurs once the critical span is reached, often involving the failure of the main roof strata.
- c. Air blast: This is a phenomenon where a large-scale roof collapse displaces a massive volume of air rapidly through the mine workings, creating a high-pressure wind blast; it is a result of a fall, not the fall itself.
- d. Rock burst: This is a violent, explosive failure of rock caused by the sudden release of accumulated elastic strain energy, typically occurring in deep mines under high geostatic pressure, rather than simply due to the withdrawal of supports.
Protodyakonov Index test is an indirect method for determination of:
A)
Shear strength of coal/rocks
B)
Young Modulus of coal/rocks
C)
Compressive strength of coal/rocks
D)
Tensile strength of coal/rocks
The Protodyakonov Index (also known as the Rock Strength Index or f) is a widely used empirical method in rock mechanics, particularly in mining engineering, to estimate the strength of rock masses. It is an indirect method used to determine the Uniaxial Compressive Strength (UCS) of the rock. The test involves measuring the amount of force required to crush a specific volume of rock or observing the fragmentation of the rock under a specific load. The index provides a numerical value that correlates directly to the compressive strength of the rock, allowing engineers to estimate support requirements for tunnels and mine galleries without performing expensive and time-consuming laboratory UCS tests on every sample.
Why other options are incorrect:
- Shear strength (a) is typically determined via direct shear tests or triaxial tests.
- Young's Modulus (b) is a measure of elasticity/stiffness, determined by the slope of the stress-strain curve during a compression test.
- Tensile strength (d) is usually determined via the Brazilian test (indirect) or direct tension tests.
The opening cut in opencast mining is called:
A)
Berm
B)
Trench
C)
Drift
D)
Box cut
In opencast (open-pit) mining, the initial excavation made to expose the ore body or coal seam and provide access for machinery is known as a 'Box cut'. It is essentially the first opening cut that allows the mining operation to transition from surface stripping to the development of the pit.
Why other options are incorrect:
- a. Berm: A berm is a horizontal ledge or platform between two benches in an open-pit mine, primarily used for safety (to catch falling rocks) or as a roadway for haulage.
- b. Trench: While a trench is an excavation, in mining terminology, it usually refers to a narrow exploration cut used for sampling or prospecting, not the primary opening cut of a mine.
- c. Drift: A drift is a horizontal underground opening that follows a vein or seam; it is a term associated with underground mining, not opencast mining.
For a circular opening of radius a, where the far –field stress value is P. The radial and tangential stresses at a distance r from the centre of the opening are
A)
σr = 0, σt = P(1 + a^2/r^2)
B)
σr = P(1 - a^2/r^2), σt = P(1 + a^2/r^2)
C)
σr = 2P(1 - a^2/r^2), σt = P(1 + a^2/r^2)
D)
σr = 3P, σt = 0
This problem refers to the Kirsch solution for a circular hole in an infinite elastic plate subjected to a hydrostatic (uniform) far-field stress P.
1. **Kirsch Equations for Hydrostatic Stress**: When a circular opening of radius 'a' is created in a rock mass subjected to a uniform far-field stress P (where σx = σy = P), the stress distribution around the hole is given by:
- Radial Stress (σr): σr = P(1 - a²/r²)
- Tangential/Hoop Stress (σt): σt = P(1 + a²/r²)
2. **Verification at Boundaries**:
- At the boundary of the opening (r = a):
σr = P(1 - a²/a²) = P(1 - 1) = 0. This is correct as the boundary of an unsupported opening is stress-free.
σt = P(1 + a²/a²) = P(1 + 1) = 2P. This shows the stress concentration factor is 2 at the wall.
- At the far-field (r → ∞):
σr = P(1 - 0) = P
σt = P(1 + 0) = P
This matches the given far-field stress condition.
3. **Evaluating Options**:
- Option (a) is incorrect because it suggests σr is always 0, which only happens at the boundary (r=a).
- Option (b) matches the derived Kirsch equations perfectly.
- Option (c) is incorrect as it introduces a coefficient of 2 for σr, which violates the far-field boundary condition.
- Option (d) is incorrect as it provides constant values regardless of the distance r.
Which of the following factor is considered for calculation of cycle time of excavating machine such as shovel, drag line etc.?
A)
Swell factor
B)
Bucket factor
C)
Swing factor
D)
Drill factor
Cycle time for excavating machinery (like shovels and draglines) is the total time taken to complete one full sequence of operations. A typical cycle consists of: 1. Digging/Loading, 2. Swinging (rotating the boom/arm to the dump point), 3. Dumping, and 4. Returning (swinging back to the digging point). The 'Swing factor' (or swing angle/time) is a critical component of the cycle time calculation because the time taken to move the material from the face to the haul truck or spoil pile depends directly on the angle of rotation.
Why other options are incorrect:
- a. Swell factor: This refers to the increase in volume of material when it is excavated from its natural state to a loose state. It affects the 'payload' or 'capacity' calculation, not the 'cycle time'.
- b. Bucket factor: This is a coefficient used to determine the actual volume of material a bucket carries relative to its rated capacity (fill factor). It affects productivity/volume per cycle, not the time taken for the cycle.
- d. Drill factor: This relates to drilling and blasting operations, which are separate processes from the excavation cycle of a shovel or dragline.
Passion’s ration can be expressed as:
A)
Lateral strain/ Longitudinal strain
B)
Longitudinal strain / Lateral strain
C)
Major principal stress/ Minor principal stress
D)
Normal stress/ Shear stress
The question contains a typographical error where 'Passion's ration' is written instead of 'Poisson's ratio'. Poisson's ratio (denoted by the Greek letter ν) is a fundamental material property in rock mechanics and elasticity. It is defined as the negative ratio of transverse (lateral) strain to axial (longitudinal) strain when a material is stretched or compressed in one direction. Mathematically, it is expressed as: ν = -(Lateral Strain / Longitudinal Strain). Since the options provide the ratios without the negative sign (which is standard in multiple-choice formats to indicate the magnitude of the relationship), option (a) is the correct definition.
Why other options are incorrect:
- Option (b) is the reciprocal of Poisson's ratio.
- Option (c) refers to the stress ratio, often used in Mohr-Coulomb failure criteria, but not Poisson's ratio.
- Option (d) describes the tangent of the angle of stress or is related to the definition of shear modulus, but not Poisson's ratio.
Tributary area method for stress estimation is valid for:
A)
Caving with Longwall
B)
Depillaring
C)
Development
D)
All cases
The Tributary Area Method (TAM) is a simplified approach used in rock mechanics to estimate the vertical stress acting on a pillar. It assumes that the pillar supports the entire weight of the rock column directly above it, plus a proportional share of the weight from the surrounding excavated areas (the 'tributary' area).
1. Why 'Development' is correct: During the development stage of a mine (e.g., creating a grid of pillars and galleries), the strata are generally assumed to be intact and the load is distributed statically. The TAM is most valid here because the pillars are designed to support the overburden without the complex dynamic stress redistributions associated with active caving.
2. Why 'Caving with Longwall' is incorrect: In longwall mining, the roof is intentionally collapsed (caved) behind the face. This creates a 'goaf' area. The stress is redistributed into a 'front abutment' and 'side abutment' pressure, which is far more complex than the simple vertical load distribution assumed by TAM.
3. Why 'Depillaring' is incorrect: Depillaring involves the systematic removal of pillars. This causes massive stress shifts, creating high-stress concentrations on the remaining pillars (abutment stresses) and potential instability. The static assumption of the Tributary Area Method fails to account for these dynamic stress transfers.
Therefore, the Tributary Area Method is a conservative estimation tool primarily valid for the initial development phase of pillar layouts.
Which of the following diagram can represent one aspect of bi-axial stress acting on a point with respect to a set of reference axes?
A)
Mohr’s circle diagram
B)
Rose diagram
C)
Intraformational shear diagram
D)
Goodman diagram
Mohr circle represents biaxial stress state w.r.t reference axes.
Mining method to protect the surface structure-
A)
Wide stall method
B)
Non effective width (NEW) of extraction method
C)
Both (a) & (b)
D)
None
In underground mining, surface protection is critical when mining beneath structures (like buildings, railways, or rivers). The 'Non-Effective Width' (NEW) concept is a specialized extraction method used to prevent surface subsidence. It involves leaving specific pillars or strips of coal/ore such that the width of the extracted area does not exceed a critical limit (the 'effective width'). If the width of the extraction is kept below this critical threshold, the overlying strata can bridge over the void, preventing the subsidence trough from reaching the surface and thereby protecting surface structures.
Option (a) 'Wide stall method' typically refers to a layout that increases the width of the extraction area, which generally increases the risk of surface subsidence rather than protecting against it. Therefore, the Non-Effective Width method is the technically correct approach for surface protection.
In longwall caving, the caving height is calculated from:
A)
Bulking factor and width of the longwall face
B)
Height of extraction and width of the longwall face
C)
Height of extraction and bulking factor
D)
Seam thickness and length of the panel
In longwall caving (also known as longwall collapse), the 'caving height' refers to the height of the strata that collapses into the goaf (the void left after coal extraction). The volume of the void created is determined by the height of extraction (the thickness of the seam being removed). However, as the overlying rock strata break and collapse, they undergo 'bulking'—meaning the broken rock occupies a larger volume than the original solid rock. The bulking factor is the ratio of the volume of the broken rock to the volume of the original solid rock. Therefore, the height to which the strata must cave to fill the void is a direct function of the height of extraction and the bulking factor of the material. Mathematically, if H is the height of extraction and B is the bulking factor (where B > 1), the caving height is related to the volume required to fill the void based on these two parameters.
Compressive strength of the rock can be expressed as:
A)
σ = Fc / A , where Fc is the failure load, and A is cross sectional area
B)
σ = A / Fc , where Fc is the failure load, and A is cross sectional area
C)
σ = Fc / V , where Fc is the failure load, and A is the Volume in m3
D)
σ = V / Fc , where Fc is the failure load, and A is the Volume in m3
In rock mechanics and materials science, compressive strength (σ) is defined as the maximum compressive stress that a material can withstand before failure. Stress is fundamentally defined as the force applied per unit area.
1. Formula derivation: Stress (σ) = Force (F) / Area (A).
2. In the context of compressive strength, the force used is the 'failure load' (Fc), which is the load at which the rock specimen breaks or yields.
3. The area (A) refers to the cross-sectional area of the specimen perpendicular to the direction of the applied load.
Evaluating the options:
- Option (a) correctly follows the formula σ = Fc / A.
- Option (b) is the reciprocal of the stress formula (Area/Force), which is incorrect.
- Option (c) divides load by volume, which does not represent stress (it would be load per unit volume).
- Option (d) divides volume by load, which is physically meaningless in the context of strength.
Punch shear test is used to determine:
A)
Tri-axial compressive strength
B)
Tensile strength
C)
Shear strength
D)
None of the above
The Punch Shear Test (also known as the Brazilian Test or Indirect Tensile Test in various contexts of rock mechanics) is specifically designed to determine the indirect tensile strength of rock samples. Because rocks are brittle and typically much weaker in tension than in compression, it is difficult to apply a direct uniaxial tensile load. In a punch shear or indirect tensile test, a cylindrical sample is loaded compressively along its diameter. This creates a transverse tensile stress perpendicular to the loading axis, causing the rock to split vertically. By measuring the load at which the sample fails, the indirect tensile strength can be calculated.
Why other options are incorrect:
- a. Tri-axial compressive strength is determined using a Tri-axial cell where the sample is subjected to confining pressure.
- c. Shear strength is typically determined using a Direct Shear Test or a Tri-axial test by analyzing the failure plane.
- d. This is incorrect as option b is the standard application of this test method.
With the increase in height, the strength of pillar:
A)
increases
B)
decreases
C)
is constant
D)
does not show any trend
In mining engineering and rock mechanics, the strength of a pillar is heavily dependent on its width-to-height (w/h) ratio. The strength of a pillar is inversely proportional to its height for a given width. As the height of the pillar increases, the w/h ratio decreases, making the pillar more slender. Slender pillars are more susceptible to buckling, lateral deformation, and the influence of structural discontinuities (joints/cleats) within the rock mass, which significantly reduces their overall load-bearing capacity. Most empirical formulas for pillar strength (such as the Obert-Duvall or Salamon-Munro formulas) incorporate the height in the denominator or as part of a ratio where an increase in height leads to a decrease in calculated strength.
The linear relationship between stress and strain can be represented by:
A)
σ = E * ε , where,ε is strain, is applied stress and E is modulus of elasticity
B)
ε = σ / E, where, is strain, is applied stress and E is modulus of elasticity
C)
E = σ / ε , where, is strain, is applied stress and E is modulus of elasticity
D)
σ = E / ε , where, is strain, is applied stress and E is modulus of elasticity
The question asks for the linear relationship between stress and strain, which is defined by Hooke's Law. Hooke's Law states that within the elastic limit of a material, the stress (σ) is directly proportional to the strain (ε). The constant of proportionality is known as the Modulus of Elasticity (E), also called Young's Modulus. Mathematically, this is expressed as σ ∝ ε, or σ = E * ε.
Analyzing the options:
- Option (a) σ = E * ε is the standard mathematical representation of Hooke's Law.
- Option (b) ε = σ / E is mathematically equivalent to σ = E * ε, but in the context of defining the 'relationship' (the governing law), the stress is typically expressed as a function of strain and the material property (E).
- Option (c) E = σ / ε is the formula used to calculate the Modulus of Elasticity, but it is a definition of the constant rather than the representation of the linear relationship between the two variables.
- Option (d) σ = E / ε is mathematically incorrect as it suggests an inverse relationship.
In engineering and rock mechanics textbooks, the primary linear constitutive equation is written as σ = Eε.
Rock mass classification is needed:
A)
For the assessment of stability of the mines
B)
For division of rock mass into group of similar behaviour
C)
For design of optimum support system in mines and tunnels
D)
All of the above
Rock mass classification systems (such as RMR - Rock Mass Rating, Q-system, and GSI - Geological Strength Index) are essential tools in rock mechanics and mining engineering for the following reasons:
1. **Assessment of Stability (Option a):** Classification systems provide a quantitative way to estimate the stand-up time of an unsupported excavation and the overall stability of the mine workings based on rock quality.
2. **Grouping by Behavior (Option b):** Because rock masses are heterogeneous, classification allows engineers to categorize different sections of a mine into groups with similar mechanical behaviors (e.g., 'Very Good', 'Fair', or 'Poor' rock), simplifying the engineering approach across large sites.
3. **Design of Support Systems (Option c):** The primary practical application of these systems is to determine the type and density of support required (e.g., rock bolts, shotcrete, or steel sets) to ensure the safety of tunnels and mine galleries, preventing over-design (which is costly) or under-design (which is dangerous).
Since all three statements are primary objectives of rock mass classification, option 'd' is the correct choice.
Dimension of modulus of elasticity (E) expressed with L, M and T is
A)
M L-1 T-2
B)
M L-1 T-1
C)
M L T-1
D)
M L T-2
The Modulus of Elasticity (E), also known as Young's Modulus, is defined as the ratio of tensile or compressive stress to the longitudinal strain.
1. **Formula**: E = Stress / Strain
2. **Stress**: Stress is defined as Force per unit Area.
- Force (F) = mass × acceleration = [M] × [L T⁻²] = [M L T⁻²]
- Area (A) = [L²]
- Therefore, Stress = [M L T⁻²] / [L²] = [M L⁻¹ T⁻²]
3. **Strain**: Strain is the ratio of change in length to original length.
- Strain = [L] / [L] = [Dimensionless] (or [M⁰ L⁰ T⁰])
4. **Calculation for E**:
- E = [M L⁻¹ T⁻²] / [1] = [M L⁻¹ T⁻²]
Comparing this result to the options:
- Option (a) M L⁻¹ T⁻² matches our derivation.
- Option (b) M L⁻¹ T⁻¹ is incorrect (incorrect time dimension).
- Option (c) M L T⁻¹ is incorrect (incorrect length and time dimensions).
- Option (d) M L T⁻² is the dimension of Force, not Modulus of Elasticity.
The plane on which the value of shear stress becomes zero, such planes are called?
A)
Vertical plane
B)
Horizontal plane
C)
Principal plane
D)
Normal plane
In rock mechanics and strength of materials, the state of stress at a point is described by a stress tensor. For any given point in a stressed body, there exist three mutually perpendicular planes on which the shear stress is zero. These specific planes are defined as the 'Principal Planes'. The normal stresses acting on these planes are called 'Principal Stresses' (typically denoted as σ1, σ2, and σ3).
Reasoning for other options:
- a. Vertical plane: A vertical plane may or may not have zero shear stress depending on the orientation of the applied loads.
- b. Horizontal plane: Similarly, a horizontal plane only has zero shear stress if it happens to coincide with a principal plane.
- d. Normal plane: This is a general term for any plane perpendicular to a specific axis; it does not inherently imply that shear stress is zero.
Goaf edge support is used to prevent:
A)
Stress development from goaf
B)
Goaf encroachment
C)
Spontaneous heating
D)
Roof fall at goaf
In underground mining, particularly in longwall or bord-and-pillar mining with caving, the 'goaf' is the area where the mineral has been extracted and the roof has collapsed. 'Goaf encroachment' occurs when the broken roof material (rubble) from the goaf spills or slides forward into the active working face or the gateroads. This can block ventilation, obstruct access, and create hazardous working conditions. Goaf edge supports (such as packing, pillars, or specialized supports) are specifically installed at the boundary between the active roadway and the goaf to act as a physical barrier, thereby preventing the goaf material from encroaching into the roadway.
Why other options are incorrect:
- Option (a): Stress development is a systemic geological result of extraction; while supports manage stress, 'edge support' specifically targets the physical boundary of the goaf.
- Option (c): Spontaneous heating is a chemical process related to oxidation and ventilation; it is managed by sealing or inertization, not by physical edge supports.
- Option (d): While roof falls are a general concern, 'goaf edge support' is specifically designed to stop the lateral movement of the goaf material (encroachment) rather than just supporting the immediate roof of the roadway.
In a Brazilian test, the diameter of the sample was 50 mm and the thickness is 25 mm. If the failure load occurs is of 1964.28 kg, than the tensile strength of the specimen will be:
A)
9.99 kg/cm2
B)
99.9 kg/cm2
C)
999 kg/cm2
D)
0.999 kg/cm2
Brazilian tensile =2P/pi D t =2*1964.28/(pi*5*2.5)cm ~100 kg/cm2 ~99.9.
The concept suggested by Deere to quantify discontinuity spacing in rock masses:
A)
RMR
B)
Q-system
C)
RQD
D)
CMRR
The Rock Quality Designation (RQD) was introduced by Don L. Deere in 1964. It is a standard measure used in rock mechanics and geotechnical engineering to quantify the degree of jointing or discontinuity spacing in a rock mass. It is calculated as the sum of the lengths of core pieces longer than 10 cm divided by the total length of the core run, expressed as a percentage.
Why other options are incorrect:
- a. RMR (Rock Mass Rating): Developed by Bieniawski, it is a comprehensive classification system that includes RQD as one of its parameters, but it is not the specific concept suggested by Deere.
- b. Q-system: Developed by Barton et al., it is a rock mass classification system based on six parameters, but it is not the Deere concept.
- d. CMRR (Coal Mine Roof Rating): Specifically developed for coal mine roof strata, which is a specialized application and not the general concept introduced by Deere.
The correct formula for determination of RQD is:
A)
RQD = (Σ core length x ≥ 10 cm / total length of core) * 100
B)
RQD = (Σ core length x ≥ 100 cm / total length of core) * 10
C)
RQD = (Σ core length x ≥ 10 mm / total length of core) * 100
D)
RQD = (Σ core length x ≥ 100 mm / total length of core) * 10
RQD stands for Rock Quality Designation, a system of rock mass classification developed by Deere in 1964. It is used to quantify the degree of jointing or fracture in a rock mass. The standard definition of RQD is the sum of the lengths of core pieces that are 10 cm (100 mm) or longer, divided by the total length of the core run, expressed as a percentage.
Evaluating the options:
- Option (a): Correct. It uses the standard threshold of 10 cm and multiplies by 100 to get a percentage.
- Option (b): Incorrect. 100 cm is too large a threshold, and the multiplier is 10 instead of 100.
- Option (c): Incorrect. 10 mm (1 cm) is too small a threshold; this would include almost all fragments, failing to distinguish between fractured and intact rock.
- Option (d): Incorrect. While 100 mm is equivalent to 10 cm, the multiplier is 10 instead of 100, which would not yield a percentage value.
What is the relationship between break-even stripping ratio (BESR) and ordinary stripping ratio (OSR)?
A)
BESR < OSR
B)
BESR = OSR
C)
BESR > OSR
D)
No relation
To understand the relationship between the Break-Even Stripping Ratio (BESR) and the Ordinary Stripping Ratio (OSR), we must define both terms in the context of open-pit mining:
1. **Ordinary Stripping Ratio (OSR):** This is the actual ratio of waste removed to the amount of ore extracted during a specific period or for a specific part of the pit. It is a physical measurement of the current mining operation (OSR = Volume of Waste / Volume of Ore).
2. **Break-Even Stripping Ratio (BESR):** This is the maximum allowable stripping ratio at which the cost of extracting the ore (including the cost of removing the overlying waste) is exactly equal to the value of the ore recovered. It represents the economic limit of the pit. The formula is generally: BESR = (Value of Ore - Production Cost of Ore) / Stripping Cost of Waste.
**Relationship:**
For an open-pit mine to be economically viable and profitable, the actual amount of waste being removed (OSR) must be less than the maximum amount of waste that can be removed without incurring a loss (BESR).
- If OSR < BESR: The operation is profitable.
- If OSR = BESR: The operation is at the break-even point (zero profit).
- If OSR > BESR: The operation is losing money.
Therefore, for a sustainable and operational mine, the Break-Even Stripping Ratio (the theoretical limit) must be greater than the Ordinary Stripping Ratio (the actual operational ratio).
Which one of the following is not a positive interaction
A)
Ammensalism
B)
Commensalism
C)
Mutualism
D)
Proto-cooperation
In ecology, biological interactions are categorized based on whether the participating species benefit (+), are harmed (-), or remain unaffected (0).
1. **Ammensalism (Option a):** This is an interaction where one species is harmed or inhibited (-), while the other species remains unaffected (0). Since one party is negatively impacted, it is not considered a positive interaction. Example: A large tree shading out a small plant beneath it.
2. **Commensalism (Option b):** An interaction where one species benefits (+) and the other is unaffected (0). Because there is a net benefit without harm, it is categorized as a positive interaction. Example: Remora fish attaching to sharks.
3. **Mutualism (Option c):** An interaction where both species benefit (+/+). This is a classic positive interaction. Example: Bees pollinating flowers.
4. **Proto-cooperation (Option d):** A non-obligatory interaction where both species benefit (+/+), but they can survive without each other. This is also a positive interaction. Example: Birds eating ticks off a rhinoceros.
Therefore, Ammensalism is the only option that involves a negative effect on one of the organisms.