Flow of blood in dorsal blood vessel of Earthworm is

Options

A. Backward
B. Forward
C. Sideward
D. Downward

Answer

### Step-by-Step Solution:

1. **Understanding the Circulatory System of Earthworm**:
- Earthworms have a closed circulatory system, meaning that blood is contained within blood vessels and does not flow freely in the body cavity.

2. **Identifying the Main Blood Vessels**:
- The main blood vessels in an earthworm include:
- Dorsal blood vessel
- Ventral blood vessel
- Aortic arches (which connect the dorsal and ventral vessels)

3. **Flow of Blood in the Dorsal Blood Vessel**:
- The dorsal blood vessel primarily carries blood towards the head of the earthworm.
- The flow of blood in this vessel is unidirectional, meaning it flows in one direction only.

4. **Direction of Blood Flow**:
- In the case of the dorsal blood vessel, blood flows forward, from the posterior (tail) end towards the anterior (head) end of the earthworm.

5. **Conclusion**:
- Therefore, the flow of blood in the dorsal blood vessel of the earthworm is forward.

### Final Answer:
The flow of blood in the dorsal blood vessel of the earthworm is **forward**.

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