Assertion : Aerobic respiration involves the exchange of respiratory gases twice.
Reason : Exchange occurs from lung to heart and then heart to lung.

Options

A. If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
B. If both Assertion and Reason are true ,but the Reason is
not the correct explanation of the Assertion.
C. If Assertion is true, but Reason is false
D. If both Assertion and Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "aerobic respiration involves the exchange of respiratory gases twice." This is true because aerobic respiration requires oxygen to produce energy and releases carbon dioxide as a byproduct.

2. **Identifying the Locations of Gas Exchange**:
- The assertion implies that there are two distinct locations where gas exchange occurs. In aerobic respiration, the first exchange occurs between the lungs and the blood (external respiration), and the second exchange occurs between the blood and the individual cells (internal respiration).

3. **Evaluating the Reason**:
- The reason provided states that "exchange occurs from lung to heart and then heart to lung." This is misleading. While the heart plays a crucial role in circulating blood, it is not directly involved in the gas exchange process. The gas exchange primarily occurs in the lungs and the tissues of the body, not between the lungs and the heart.

4. **Conclusion**:
- Therefore, the assertion is true because aerobic respiration does involve two exchanges of gases. However, the reason is false because it incorrectly describes the locations of gas exchange. The correct conclusion is that the assertion is true, but the reason is false.

### Final Answer:
- Assertion: True
- Reason: False