The average size of diatoms go on decreasing as divisions progress. The original size is restored by

Options

A. statospores
B. auxospores
C. zoospores
D. microspores

Answer

To solve the question regarding how the average size of diatoms is restored after it decreases during divisions, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Diatom Division**:
- Diatoms reproduce asexually through cell division, which leads to a decrease in their average size over successive generations. This is because each daughter cell is smaller than the parent cell.

2. **Identifying the Restoration Process**:
- To restore the original size of diatoms, a specific reproductive process is involved. This process typically occurs through sexual reproduction.

3. **Recognizing the Role of Zygotes**:
- During sexual reproduction, diatoms form zygotes. The zygote is a fertilized cell that results from the fusion of gametes.

4. **Formation of Auxospores**:
- The zygote grows in size and eventually develops into a rejuvenation cell known as an auxospore. This auxospore is larger and restores the original size of the diatom.

5. **Evaluating the Options**:
- Now, we can evaluate the given options:
- **Stato spores**: These are resting spores and do not restore size. (Incorrect)
- **Auxospores**: Correct answer, as they are formed from zygotes and restore size.
- **Zoospores**: These are asexual spores and do not contribute to size restoration. (Incorrect)
- **Microspores**: These are also not related to size restoration. (Incorrect)

6. **Conclusion**:
- Based on the analysis, the correct answer is **Auxospores**.

### Final Answer:
The original size of diatoms is restored by **Auxospores**.