One of the chief reasons among the following for the depletion in the number of species making it endangered is :

Options

A. Greenhouse effect
B. Habitat destruction
C. Overhunting and poaching
D. Competition and predation.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for one of the chief reasons for the depletion of species that leads to them becoming endangered.

2. **Identifying the Evil Quartet**: The video mentions the "evil quartet," which refers to four major reasons for species depletion: habitat loss and fragmentation, overexploitation, alien species invasion, and co-extinction.

3. **Evaluating Each Reason**:
- **Habitat Loss and Fragmentation**: This refers to the destruction of natural habitats, such as forests, which leads to animals losing their homes. This is particularly significant for species that require large territories and migratory birds. This is a major cause of species becoming endangered.
- **Overexploitation**: This involves excessive hunting or harvesting of species, leading to their decline. Examples include the extinction of the passenger pigeon and steller's sea cow due to overhunting.
- **Alien Species Invasion**: The introduction of non-native species can disrupt local ecosystems. Examples include Parthenium weed and water hyacinth in India, which outcompete native species.
- **Co-extinction**: This occurs when the extinction of one species leads to the extinction of another species that is dependent on it.

4. **Determining the Chief Reason**: Among these reasons, habitat loss and fragmentation is highlighted as the most critical cause of species depletion. It directly affects the living conditions of many species, leading to their endangerment.

5. **Conclusion**: Based on the analysis, the correct answer to the question is habitat loss and fragmentation.

### Final Answer:
The chief reason for the depletion in the number of species making them endangered is **habitat loss and fragmentation**.

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