Nephridia are excretory organs of

Options

A. frog
B. rat
C. earthworm
D. cockroach

Answer

### Step-by-Step Solution:

1. **Identify the Organ**: The question asks about nephridia, which are excretory organs.

2. **Determine the Organism**: Nephridia are primarily found in earthworms. They serve a similar function to kidneys in other organisms.

3. **Types of Nephridia**: In earthworms, nephridia are categorized into three types:
- **Pharyngeal Nephridia**: Located in segments 4 to 6.
- **Integumentary Nephridia**: Found from segment 7 to the last segment.
- **Septal Nephridia**: Present on the septum between segments 14 and 16.

4. **Comparison with Other Organisms**: While discussing other organisms:
- **Cockroaches**: They possess Malpighian tubules for excretion, not nephridia.
- **Frogs and Rats**: They have kidneys as their excretory organs.

5. **Conclusion**: Based on the information, nephridia are the excretory organs of earthworms.

### Final Answer:
Nephridia are excretory organs of **earthworms**.

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