Dodo, passenger pigeon and Steller's sea cow became extinct in the last 500 years due to
(a) Habitat destruction
(b) Over-exploitation
(c) Bird-flu virus infection
(d) Pollution

Options

A. habitat destruction
B. over-exploitation
C. bird-flu virus infection
D. pollution

Explanation

**Step-by-Step Solution:**

1. **Identify the Organisms**: The question mentions three specific organisms: Dodo, Passenger Pigeon, and Steller's Sea Cow. All of these species are known to have gone extinct in the last 500 years.

2. **Understand the Causes of Extinction**: The question provides four options that could potentially explain the extinction of these species:
- (a) Habitat destruction
- (b) Over-exploitation
- (c) Bird-flu virus infection
- (d) Pollution

3. **Analyze Each Option**:
- **Habitat Destruction**: While habitat destruction is a significant factor for many extinctions, it is not the primary cause for the extinction of the Dodo, Passenger Pigeon, and Steller's Sea Cow.
- **Over-exploitation**: This refers to the excessive hunting or harvesting of a species. Historical records indicate that these species were heavily hunted by humans, leading to their decline and eventual extinction.
- **Bird-flu Virus Infection**: There is no evidence that bird flu was a factor in the extinction of these specific species.
- **Pollution**: While pollution affects many species, it was not the direct cause of extinction for the Dodo, Passenger Pigeon, and Steller's Sea Cow.

4. **Conclusion**: Based on the analysis, the most accurate reason for the extinction of the Dodo, Passenger Pigeon, and Steller's Sea Cow is (b) Over-exploitation. This excessive exploitation led to a significant reduction in their populations, making them vulnerable to extinction.

5. **Final Answer**: Therefore, the correct answer is (b) Over-exploitation.

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