Which is the only vein that carries oxygenated blood?

Options

A. Hepatic vein
B. Pulmonary vein
C. Cardiac vein
D. Renal vein

Answer

### Step-by-Step Solution:

1. **Understanding Veins and Their Function**:
- Veins are blood vessels that typically carry deoxygenated blood from the body back to the heart.

2. **Identifying the Exception**:
- While most veins carry deoxygenated blood, there is an exception in the circulatory system.

3. **The Role of the Lungs**:
- Blood that is deoxygenated travels from the heart to the lungs via the pulmonary artery. In the lungs, carbon dioxide is exchanged for oxygen.

4. **Oxygenated Blood Return**:
- After the blood is oxygenated in the lungs, it needs to return to the heart. This is where the special vein comes into play.

5. **Identifying the Vein**:
- The vein responsible for carrying oxygenated blood from the lungs back to the heart is called the pulmonary vein.

6. **Conclusion**:
- Therefore, the only vein that carries oxygenated blood is the pulmonary vein.

### Final Answer:
The only vein that carries oxygenated blood is the **pulmonary vein**.

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