Coelosepta are absent in earthworm:-

Options

A. In Clitellar segment
B. In 1st four segments
C. Between 9th and 10th segment
D. 2 and 3 both

Answer

### Step-by-Step Solution:

1. **Understanding Coelosepta**: Coelosepta are internal septa or partitions found in segmented animals like earthworms. They help in the division of the coelomic cavity into segments.

2. **Identifying Segments in Earthworm**: In earthworms, the body is divided into segments. Each segment typically contains coelosepta, but there are exceptions.

3. **Segments Without Coelosepta**: The question specifically asks where coelosepta are absent in earthworms. It is known that coelosepta are absent in the first four segments of the earthworm's body.

4. **Additional Absence of Coelosepta**: Besides the first four segments, coelosepta are also absent between the 9th and 10th segments. This means that there are two specific regions in the earthworm where coelosepta do not exist.

5. **Clitellum**: The clitellum is a glandular, saddle-shaped region in certain annelids, including earthworms. It is important to note that the clitellum is located in the segments where coelosepta are absent.

6. **Conclusion**: Therefore, the correct answer is that coelosepta are absent in the first four segments and between the 9th and 10th segments. Thus, the correct option is that both the 2nd and 3rd options are correct.

### Final Answer:
Coelosepta are absent in the first four segments and between the 9th and 10th segments of the earthworm. Therefore, the answer is option 4: both 2nd and 3rd options are correct.