Assertion : Thigh muscles can get tired but not the muscles of ventricle of heart.
Reason : Muscles of thigh are voluntary whereas that of heart are involuntary muscles.

Options

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

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that thigh muscles can get tired, but the muscles of the ventricle of the heart do not get tired. This is a true statement. Thigh muscles, which are skeletal muscles, can become fatigued after prolonged use.

**Hint**: Think about activities that require prolonged use of thigh muscles, like running or cycling.

2. **Understanding the Reason**: The reason given is that thigh muscles are voluntary muscles while heart muscles are involuntary muscles. This statement is also true. Skeletal muscles (like those in the thighs) are under conscious control, while cardiac muscles (in the heart) operate automatically without conscious control.

**Hint**: Recall the difference between voluntary and involuntary muscles and their functions in the body.

3. **Analyzing the Relationship**: While both the assertion and reason are true, the reason does not adequately explain the assertion. The assertion is about the fatigue of thigh muscles, while the reason focuses on the type of muscle (voluntary vs. involuntary). The heart muscles do not tire due to their rich blood supply and high mitochondrial content, which allows for continuous ATP production.

**Hint**: Consider why the heart can keep functioning without tiring compared to skeletal muscles.

4. **Conclusion**: Therefore, the assertion is true, and the reason is true, but the reason is not the correct explanation for the assertion.

**Hint**: Reflect on how the heart's structure and function contribute to its endurance compared to skeletal muscles.

### Final Answer:
- Assertion: True
- Reason: True
- Explanation: The reason does not correctly explain the assertion.