Biodiversity loss occurs due to -
A. Habitat loss and fragmentation
B. Co-extinction
C. over-exploitation
D. Alien species invasion.

Options

A. A, B
B. A, B, C
C. B, C, D
D. A, B, C, D

Answer

### Step-by-Step Solution

1. **Identify the Causes of Biodiversity Loss**: The question asks for the factors contributing to biodiversity loss. The options provided are:
- A. Habitat loss and fragmentation
- B. Co-extinction
- C. Over-exploitation
- D. Alien species invasion

2. **Analyze Each Option**:
- **Option A: Habitat loss and fragmentation**: This occurs when natural habitats are destroyed or divided into smaller, isolated patches. Activities such as road construction, dam building, and urban development lead to habitat loss, which is a significant cause of biodiversity loss.

- **Option B: Co-extinction**: This refers to the phenomenon where the extinction of one species leads to the extinction of another species that depends on it. For example, if a predator species goes extinct, the prey species may also decline due to the lack of natural control, leading to further biodiversity loss.

- **Option C: Over-exploitation**: This involves the excessive use of natural resources, such as overfishing or deforestation, which can lead to the depletion of species and habitats. For instance, over-harvesting of certain species can lead to their extinction.

- **Option D: Alien species invasion**: This occurs when non-native species are introduced to an ecosystem, often leading to competition with native species, which can result in the decline or extinction of native species.

3. **Conclusion**: All four options (A, B, C, and D) are valid causes of biodiversity loss. Therefore, the correct answer is that biodiversity loss occurs due to:
- A. Habitat loss and fragmentation
- B. Co-extinction
- C. Over-exploitation
- D. Alien species invasion

### Final Answer: All of the above options (A, B, C, D) contribute to biodiversity loss.

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