Primary function of enteronephric nephridia of Pheretima is

Options

A. osmoregulation
B. excretion of nitrogenous wastes
C. respiration
D. Iocomotion

Explanation

**Step-by-Step Solution:**

1. **Identify the Organism**: The question refers to "Pheretima," which is a genus of earthworms. Understanding that we are discussing earthworms is crucial for answering the question correctly.

2. **Understand the Excretory System**: In earthworms, the primary excretory organs are called nephridia (singular: nephredium). It is important to know that there are different types of nephridia, including segmental, integumentary, and pharyngeal nephridia.

3. **Determine the Function of Nephridia**: The primary function of nephridia in earthworms is to regulate the volume and composition of body fluids. This process is known as osmoregulation.

4. **Differentiate Between Excretion and Osmoregulation**: While nephridia do help in the excretion of nitrogenous wastes, such as ammonia, their primary role is to maintain homeostasis by regulating body fluids. This distinction is important to avoid confusion.

5. **Conclude the Primary Function**: Therefore, the primary function of enteronephric nephridia in Pheretima (earthworms) is osmoregulation.

**Final Answer**: The primary function of enteronephric nephridia of Pheretima is osmoregulation.

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