Assertion : During exercise, a person undergoes fatigue very soon.
Reason : During this period , muscle fibres undergo oxygen debt.

Options

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

Answer

To solve the question, we need to analyze the assertion and the reason provided:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "During exercise, a person undergoes fatigue very soon."
- This is true because during intense physical activity, muscles require more energy and oxygen. When the demand exceeds the supply, fatigue sets in quickly.

2. **Understanding the Reason**:
- The reason states that "During this period, muscle fibers undergo oxygen debt."
- This is also true. Oxygen debt occurs when the body cannot supply enough oxygen to the muscles during prolonged exercise, leading to anaerobic respiration. This results in the production of lactic acid, which contributes to muscle fatigue.

3. **Connecting Assertion and Reason**:
- The reason explains why the assertion is true. The lack of oxygen during exercise leads to anaerobic conditions, causing fatigue due to lactic acid accumulation.

4. **Evaluating the Options**:
- Based on the analysis, both the assertion and reason are true, and the reason correctly explains the assertion.
- Therefore, the correct option is: "Both assertion and reason are true, and reason is the correct explanation of assertion."

### Final Answer:
- The correct answer is: **Both assertion and reason are true, and reason is the correct explanation of assertion.**

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