Blood is poured into the left atrium through

Options

A. superior vena cava
B. pulmonary vein
C. inferior vena cava
D. pulmonary artery

Explanation

To answer the question "Blood is poured into the left atrium through," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Heart Structure**: The human heart consists of four chambers: the right atrium, left atrium, right ventricle, and left ventricle. The right side of the heart deals with deoxygenated blood, while the left side handles oxygenated blood.

2. **Identifying Blood Flow**: Oxygenated blood comes from the lungs after it has been oxygenated. This oxygenated blood needs to return to the heart.

3. **Identifying the Vessel**: The vessel responsible for transporting oxygenated blood from the lungs to the heart is the pulmonary vein.

4. **Reasoning for the Pulmonary Vein**: Unlike most veins that carry deoxygenated blood, the pulmonary vein is unique because it carries oxygenated blood. This is an exception to the general rule of veins and arteries.

5. **Conclusion**: Therefore, the blood is poured into the left atrium through the pulmonary vein.

The final answer is: **Blood is poured into the left atrium through the pulmonary vein.**