Explanation:

- Option 1: In-situ conservation

- This refers to the conservation of species in their natural habitats.

- National Parks maintain genetic diversity by protecting ecosystems where biodiversity naturally occurs.

- It allows species to evolve naturally and adapt to changing environments.

- Correct Answer

- Option 2: Ex-situ conservation

- This involves conserving species outside their natural habitats.

- Examples include zoos, botanical gardens, and seed banks.

- Not typically what National Parks focus on for maintaining genetic diversity.

- Option 3: Gene pool

- Refers to the total genetic diversity found within a population or species.

- It is a concept, not a method of conservation.

- Option 4: None of the above

- Incorrect, as in-situ conservation is a relevant method used in National Parks.