Cryopreservation is the reservation of germplasm at very low temperature of around
(a) − 121 ∘ C
(b) − 196 ∘ C
(c) 0 ∘ C
(d) − 101 ∘ C

Options

A. `-121^(@)C`
B. `-196^(@)C`
C. `0^(@)C`
D. `-101^(@)C`

Explanation

To solve the question about the temperature at which cryopreservation occurs, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Cryopreservation**: Cryopreservation is a method used to preserve biological materials, particularly germplasm, at very low temperatures to maintain their viability.

2. **Identify the Temperature Range**: The question provides four temperature options:
- (a) −121 °C
- (b) −196 °C
- (c) 0 °C
- (d) −101 °C

3. **Recall the Standard Cryopreservation Temperature**: The commonly accepted temperature for cryopreservation is around −196 °C. This temperature is typically achieved using liquid nitrogen.

4. **Eliminate Incorrect Options**:
- Option (a) −121 °C is not low enough for effective cryopreservation.
- Option (c) 0 °C is not a cryogenic temperature.
- Option (d) −101 °C is also not low enough for effective preservation.

5. **Select the Correct Answer**: The only temperature that aligns with the standard practice of cryopreservation is (b) −196 °C.

### Final Answer:
The correct answer is (b) −196 °C.

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