One of the ex situ conservation methods for endangered species is
(a) Wildlife sanctuaries
(b) Biosphere reserves
(c) Cryopreservation
(d) National parks.

Options

A. wildlife sanctuaries
B. biosphere reserves
C. cryopreservation
D. national parks.

Answer

To solve the question regarding ex situ conservation methods for endangered species, we need to understand the definitions and differences between in situ and ex situ conservation methods. Here's a step-by-step solution:

### Step-by-Step Solution:

1. **Understand the Types of Conservation**:
- Conservation methods are broadly classified into two categories: in situ and ex situ.
- In situ conservation refers to the preservation of species in their natural habitats, while ex situ conservation involves the preservation of species outside their natural habitats.

2. **Identify the Options**:
- The options given are:
- (a) Wildlife sanctuaries
- (b) Biosphere reserves
- (c) Cryopreservation
- (d) National parks

3. **Analyze Each Option**:
- **Wildlife Sanctuaries**: These are areas where animals are protected in their natural environment. This is an in situ conservation method.
- **Biosphere Reserves**: These are designated areas that aim to conserve biodiversity and promote research. This is also an in situ conservation method.
- **Cryopreservation**: This method involves preserving genetic material (like seeds, gametes, or cells) at extremely low temperatures outside of their natural habitat. This is an ex situ conservation method.
- **National Parks**: Similar to wildlife sanctuaries, these are protected areas where species are conserved in their natural environment. This is an in situ conservation method.

4. **Determine the Correct Answer**:
- Since we are looking for an ex situ conservation method, the only option that fits this definition is **(c) Cryopreservation**.

5. **Conclusion**:
- Therefore, the correct answer is **(c) Cryopreservation**.