What is true about vein?

Options

A. All veins carry deoxygenated blood
B. All veins carry oxygenated blood
C. They carry blood from organs towards heart
D. They carry blood from heart towards organs

Answer

**Step-by-Step Solution:**

1. **Understanding the Function of Veins:**
- Veins are blood vessels that primarily carry blood from various parts of the body back to the heart. This is a fundamental function of veins.

2. **Identifying the Type of Blood Carried by Veins:**
- Most veins carry deoxygenated blood, which is blood that has delivered oxygen to the tissues and is returning to the heart for re-oxygenation. However, there is an exception to this rule.

3. **Recognizing the Exception:**
- The pulmonary veins are the exception as they carry oxygenated blood from the lungs to the left atrium of the heart. This is crucial to note because it differentiates pulmonary veins from other veins in the body.

4. **Clarifying Misconceptions:**
- It is incorrect to say that all veins carry oxygenated blood; this statement is false. Arteries are responsible for carrying oxygenated blood away from the heart to the organs.

5. **Summarizing the True Statement:**
- The true statement about veins is that they carry blood from the organs back towards the heart. This can be exemplified by the superior vena cava and inferior vena cava, which transport deoxygenated blood from the upper and lower parts of the body, respectively, back to the heart.

6. **Final Conclusion:**
- Therefore, the correct answer to the question "What is true about veins?" is that they carry blood from the organs towards the heart.