Which of the following annelid is dioecious?

Options

A. Nereis
B. Pheretima
C. Hirudinaria
D. Both (2) and (3)

Explanation

To determine which of the following annelids is dioecious, we need to analyze the reproductive characteristics of the given options: Ferritima, Hedonaria, and Nereis.

### Step-by-Step Solution:

1. **Understand Dioecious vs. Monoecious:**
- Dioecious organisms have male and female reproductive organs in separate individuals.
- Monoecious organisms have both male and female reproductive organs in the same individual.

2. **Evaluate Ferritima:**
- Ferritima is known to be monoecious, meaning it has both male and female sex organs in the same individual.

3. **Evaluate Hedonaria:**
- Hedonaria is also monoecious, with both male and female sex organs present in the same body.

4. **Evaluate Nereis:**
- Nereis is dioecious, meaning it has separate male and female individuals. They release their gametes into the water for external fertilization.

5. **Conclusion:**
- The only dioecious annelid among the options provided is Nereis.

### Final Answer:
The dioecious annelid is **Nereis**.

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