A technique in which sperm are stored for a long duration is

Options

A. incubator
B. cryopreservation
C. deep freezing
D. all of these

Answer

To solve the question regarding the technique used for long-term storage of sperm, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a technique that allows for the long-term storage of sperm. We need to identify the correct term that describes this process.

2. **Analyzing the Options**:
- **Incubator**: This is a device used to create a controlled environment for biological samples, but it does not specifically refer to a long-term storage technique.
- **Cryopreservation**: This is a process where cells, including sperm, are preserved by cooling them to very low temperatures, typically below the freezing point. This method maintains the viability of the cells for extended periods.
- **Defreezing**: This refers to the process of warming frozen materials back to a temperature where they can function normally. It is not a storage technique.
- **All of these**: This option suggests that all the previous options are correct, which is not the case.

3. **Identifying the Correct Answer**: Among the options, cryopreservation is the only technique specifically designed for the long-term storage of sperm by preserving them at very low temperatures.

4. **Conclusion**: The correct answer to the question is **cryopreservation**.

### Final Answer:
The technique in which sperm are stored for a long duration is **cryopreservation**.