Identify the set of collecting and distributing blood vessels in Pheretima

Options

A. Latero - oesophageal blood vessel and subneural blood vessel and commissural blood vessels
B. Dorsal blood vessel and commissural blood vessels
C. Dorsal blood vessel and ventral blood vessel
D. Ring vessels and anterior loops

Answer

To identify the set of collecting and distributing blood vessels in Pheretima, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Organism**: Pheretima is a genus of earthworms, and like other annelids, it has a closed circulatory system.

2. **Identifying Blood Vessels**: In Pheretima, there are specific blood vessels that play roles in collecting and distributing blood. The primary vessels to consider are:
- Dorsal blood vessel
- Commissural blood vessels

3. **Function of Dorsal Blood Vessel**: The dorsal blood vessel runs along the mid-dorsal line above the gut. Its main function is to collect blood from various segments of the worm through dorso-intestinal vessels and from the sub-neural blood vessels.

4. **Function of Commissural Blood Vessels**: The commissural blood vessels connect the dorsal blood vessel to the ventral blood vessel. They also give off branches called septo-intestinal branches that supply blood to the intestine.

5. **Valvular Openings**: The openings of the dorsal intestinal and commissural blood vessels into the dorsal blood vessel are valvular, which helps in regulating blood flow.

6. **Conclusion**: Based on the functions and connections of these vessels, we conclude that the correct set of collecting and distributing blood vessels in Pheretima is the **dorsal blood vessel and commissural blood vessels**.

### Final Answer:
The set of collecting and distributing blood vessels in Pheretima is the **dorsal blood vessel and commissural blood vessels**.

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