The total number of segments with all 3 types of nephridia are 

Options

A. 5
B. 10
C. 15
D. None

Answer

To solve the question regarding the total number of segments with all three types of nephridia in an earthworm, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Nephridia**:
- In earthworms, there are three types of nephridia: integumentary nephridia, pharyngeal nephridia, and septal nephridia.

2. **Identify the Segments for Each Type**:
- **Integumentary Nephridia**: Present from the 3rd segment to the last segment.
- **Pharyngeal Nephridia**: Present in the 4th, 5th, and 6th segments.
- **Septal Nephridia**: Present from the 15th segment to the last segment.

3. **Analyze the Overlap of Segments**:
- The integumentary nephridia are found starting from the 3rd segment, while the pharyngeal nephridia are only present in the 4th, 5th, and 6th segments.
- The septal nephridia only appear from the 15th segment onwards.

4. **Determine Common Segments**:
- The segments 4, 5, and 6 have both integumentary and pharyngeal nephridia, but they do not have septal nephridia.
- The segments from the 15th segment onwards have septal nephridia but do not have pharyngeal nephridia.

5. **Conclusion**:
- Since there is no segment that contains all three types of nephridia simultaneously, we conclude that there are **no segments** with all three types of nephridia present.

### Final Answer:
The total number of segments with all three types of nephridia is **none**.