Exonephric secretion in earthworm is by:-

Options

A. Septal nephridia
B. Pharyngeal nephridia
C. intergumentary nephridia
D. 2 and 3 both

Answer

**Step-by-Step Solution:**

1. **Understanding Exonephric Secretion**: Exonephric secretion refers to the process where waste products are excreted directly from the body without passing through a renal system. In this context, we are looking for the structures in earthworms that perform this function.

2. **Identifying Nephridia Types**: Earthworms have different types of nephridia, which are excretory organs. The main types mentioned are:
- Septal nephredia
- Pharyngeal nephredia
- Intergumentary nephredia
- Second and third nephredia

3. **Focusing on Intergumentary Nephredia**: Among the types listed, intergumentary nephredia are specifically noted for their role in exonephric secretion. They are small, V-shaped structures located in every segment of the earthworm.

4. **Function of Intergumentary Nephredia**: These nephredia open outwards through a nephrediopore, allowing waste products to be expelled directly from the body. Notably, they do not have nephrostomes, which are typically involved in filtering waste.

5. **Conclusion**: Since intergumentary nephredia are responsible for exonephric secretion by directly expelling waste from the body, the correct answer to the question is option 3: Intergumentary nephredia.

**Final Answer**: Exonephric secretion in earthworm is by: **Intergumentary nephredia (Option 3)**.

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