Assertion : Aerobic animals are not truly aerobic.
Reason : They produce lactic acid anaerobically.

Options

A. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. f both assertion and reason are false

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Aerobic animals are not truly aerobic." To analyze this, we need to understand what "aerobic" means. Aerobic refers to processes that require oxygen.

2. **Role of Oxygen in Respiration**: Aerobic animals utilize oxygen to break down food substances (like glucose) to produce energy. This process is known as aerobic respiration, which primarily occurs in the presence of oxygen.

3. **Anaerobic Processes**: However, aerobic animals can also undergo anaerobic processes, especially when oxygen is limited. This means that even in aerobic animals, there are conditions under which they do not rely solely on oxygen for energy production.

4. **Energy Production and Lactic Acid**: In the absence of sufficient oxygen, glucose is converted into pyruvate, which can then be further broken down into lactic acid in muscle cells. This process occurs during intense exercise when oxygen supply is inadequate.

5. **Conclusion on Assertion**: Since aerobic animals can produce energy without oxygen under certain conditions (e.g., during strenuous activity), the assertion that "aerobic animals are not truly aerobic" is correct.

6. **Understanding the Reason**: The reason states, "They produce lactic acid anaerobically." This is also true, as during anaerobic respiration, the breakdown of glucose leads to the formation of lactic acid instead of carbon dioxide and water, which are produced during aerobic respiration.

7. **Final Evaluation**: Both the assertion and the reason are correct, and the reason provides a valid explanation for the assertion. Therefore, the conclusion is that both statements are true, and the reason is the correct explanation of the assertion.