Choose the schematic diagram which properly respresents pulmonary circulation in humans.

Options

A. Left auricle `underset("blood")overset("Deoxygenated")(rarr)` Lungs `underset("blood")overset("Oxygenated")(rarr)` Right ventricle
B. Let auricle `underset("blood")overset("Oxygenated")(rarr)` Lungs `underset("blood")overset("Deoxygenated")(rarr)` Right ventricle
C. Right ventricle `underset("blood")overset("Deoxygenated")(rarr)` Lungs `underset("blood")overset("Oxygenated")(rarr)` left auricle
D. Right ventricle `underset("blood")overset("Oxygenated")(rarr)` Lungs `underset("blood")overset("Deoxygenated")(rarr)` left auricle

Explanation

To choose the schematic diagram that properly represents pulmonary circulation in humans, we need to understand the flow of blood between the heart and the lungs. Here is a step-by-step breakdown of the pulmonary circulation process:

### Step-by-Step Solution:

1. **Understanding Pulmonary Circulation**:
- Pulmonary circulation refers to the movement of blood between the heart and the lungs. It is responsible for oxygenating the blood.

2. **Starting Point - Right Atrium**:
- The process begins in the **right atrium** of the heart. This chamber receives deoxygenated blood from the body through the **superior vena cava** and **inferior vena cava**.

3. **Right Ventricle**:
- From the right atrium, blood flows into the **right ventricle**. The right ventricle is responsible for pumping this deoxygenated blood to the lungs.

4. **Pulmonary Artery**:
- The right ventricle sends the deoxygenated blood through the **pulmonary artery** to the lungs. This is the only artery that carries deoxygenated blood.

5. **Gas Exchange in the Lungs**:
- In the lungs, the blood undergoes gas exchange, where it releases carbon dioxide and absorbs oxygen. This process oxygenates the blood.

6. **Pulmonary Vein**:
- The now oxygenated blood returns to the heart via the **pulmonary veins**. This is the only vein that carries oxygenated blood.

7. **Left Atrium**:
- The oxygenated blood enters the **left atrium** of the heart through the pulmonary veins.

8. **Left Ventricle**:
- From the left atrium, blood moves into the **left ventricle**, which then pumps the oxygenated blood out to the rest of the body through the **aorta**.

### Conclusion:
To summarize, the correct schematic diagram should illustrate the flow of blood starting from the right atrium, moving to the right ventricle, then to the lungs via the pulmonary artery, returning to the left atrium through the pulmonary veins, and finally entering the left ventricle.