Metameric segmentation is

Options

A. External segmentation corresponding to internal segmentation
B. Segmentation present in only a part of the individual
C. Segmentation found in the middle part of the body
D. Posterior segmentation

Answer

**Step-by-Step Solution:**

1. **Understanding Metameric Segmentation**:
- Metameric segmentation refers to the division of an organism's body into repeated segments or metameres. This type of segmentation is characterized by the presence of both external and internal divisions that correspond to each other.

2. **Identifying the Characteristics**:
- In metameric segmentation, each segment (or metamere) contains similar structures and organs. This means that the external segmentation (what we can see) matches the internal segmentation (what is inside).

3. **Analyzing the Options**:
- **Option A**: External segmentation corresponding to internal segmentation.
- This option accurately describes metameric segmentation, as both external and internal structures are segmented in the same way.
- **Option B**: Segmentation present in only a part of the individual.
- This is incorrect because metameric segmentation occurs throughout the entire body, not just in a part.
- **Option C**: Segmentation found in the middle part of the body.
- This is also incorrect; metameric segmentation is not limited to just the middle part.
- **Option D**: Posterior segmentation.
- This option is misleading as it implies that segmentation only occurs at the posterior end, which is not true for metameric segmentation.

4. **Conclusion**:
- The correct answer is **Option A**: External segmentation corresponding to internal segmentation, as this accurately defines metameric segmentation.