In Pheretima nephridia occur in

Options

A. all segments except 1-4 and 10-14
B. all segments except first two segments
C. meganephridia in pre-clitellar and micronephridia in post-clitellar segments
D. micronephridia in all segements, meganephridia from clitellar region to end

Answer

To answer the question regarding the occurrence of nephridia in Pheretima (earthworm), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Organism**: Pheretima is a genus of earthworms that belong to the phylum Annelida. Annelids are characterized by their segmented bodies.

2. **Identify Nephridia Types**: In earthworms, nephridia are excretory organs that help in the removal of waste. There are two types of nephridia:
- **Micronephridia**: These are smaller in size, numerous, and present in each segment of the earthworm.
- **Meganephridia**: These are larger and are found in specific regions, particularly from the clitellar region to the posterior end.

3. **Locate the Clitellar Region**: The clitellum is a thickened, glandular, non-segmented part of the earthworm's body, typically found in segments 14 to 16. It plays a crucial role in reproduction.

4. **Analyze the Options**:
- **Option A**: "All segments except 1 to 4 and 10 to 14" - This is incorrect as micronephridia are present in all segments.
- **Option B**: "All segments except first two segments" - This is also incorrect for the same reason.
- **Option C**: "Meganephridia in the preclitellar and micronephridia in postclitellar segments" - This is incorrect because meganephridia are not found in the preclitellar segments.
- **Option D**: "Micronephridia in all segments and meganephridia from clitellar region to ant." - This is correct as micronephridia are indeed present in all segments, and meganephridia are found from the clitellar region to the posterior end.

5. **Conclusion**: The correct answer is **Option D**: Micronephridia in all segments and meganephridia from the clitellar region to the end.