Assertion : Woollen clothes keep the body warm in winter
Reason : Air is a bad conductor of heat.

Options

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

Explanation

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Woollen clothes keep the body warm in winter." This is true because wool is known for its insulating properties.

2. **Understanding the Reason**:
- The reason given is "Air is a bad conductor of heat." This is also true. Air does not conduct heat well, which is why it is often used as an insulator.

3. **Connecting Assertion and Reason**:
- Woollen clothes are made of fibers that create spaces filled with air. These air pockets trap heat from the body and prevent it from escaping into the colder environment outside.

4. **Conclusion**:
- Since the reason (air being a bad conductor of heat) explains why the assertion (woollen clothes keeping the body warm) is true, we can conclude that both the assertion and the reason are correct, and the reason correctly explains the assertion.

5. **Final Answer**:
- Therefore, both the assertion and the reason are correct, and the reason correctly explains the assertion.