System heart comprises

Options

A. (1) Left atrium and left ventricle.
B. (2) Left atrium and right atrium
C. .(3) Right atrium and left ventricle
D. (4) Left atrium and right ventricle

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of the Heart**:
- The human heart consists of four main chambers: the right atrium, right ventricle, left atrium, and left ventricle.

2. **Identifying the Components of the Heart**:
- The right atrium receives deoxygenated blood from the body via the superior and inferior vena cavae.
- The right ventricle pumps this blood to the lungs through the pulmonary artery for oxygenation.
- The left atrium receives oxygenated blood from the lungs via the pulmonary veins.
- The left ventricle pumps this oxygenated blood to the rest of the body through the aorta.

3. **Evaluating the Options**:
- The options provided are:
1. Left atrium and left ventricle
2. Left atrium or right ventricle
3. Right atrium and left ventricle
4. Left atrium and right atrium
5. Right ventricle and left ventricle
- We need to determine which of these combinations correctly represents the components of the heart.

4. **Analyzing Each Option**:
- **Option 1**: Left atrium and left ventricle - This option is valid as both are parts of the heart.
- **Option 2**: Left atrium or right ventricle - This option is misleading as it suggests only one of the two is part of the heart.
- **Option 3**: Right atrium and left ventricle - This combination is incorrect as they are not directly connected.
- **Option 4**: Left atrium and right atrium - This option is also incorrect as it does not include the ventricles.
- **Option 5**: Right ventricle and left ventricle - This option is valid but does not include the atria.

5. **Conclusion**:
- The best answer based on the options provided is **Option 1: Left atrium and left ventricle**. However, it is important to note that the heart comprises all four chambers: right atrium, right ventricle, left atrium, and left ventricle.