The woollen clothes keep us warm during winter because :
A. Wool is an insulator B. Wool is a conductor
C. Wool traps air D. Wool has vacuum

Options

A. A and B
B. B and C
C. C and D
D. A and C

Answer

To solve the question regarding why woollen clothes keep us warm during winter, we need to analyze the given options one by one.

### Step-by-Step Solution:

1. **Understanding Wool as an Insulator**:
- Wool is known to be a poor conductor of heat, which means it does not allow heat to pass through it easily. This property makes wool an insulator.
- **Hint**: Think about how materials are classified based on their ability to conduct heat.

2. **Trapping Air**:
- Wool has a unique structure that allows it to trap air within its fibers. This trapped air acts as an insulating layer, preventing heat from escaping from our bodies.
- **Hint**: Consider how air behaves in terms of heat transfer; it can help in insulation.

3. **Evaluating the Options**:
- **Option A**: "Wool is an insulator" - This is correct because wool does not conduct heat well.
- **Option B**: "Wool is a conductor" - This is incorrect because wool does not conduct heat; it is an insulator.
- **Option C**: "Wool traps air" - This is correct as wool fibers trap air, which helps in insulation.
- **Option D**: "Wool has vacuum" - This is incorrect because wool does not create a vacuum; it traps air instead.
- **Hint**: Compare each statement with the properties of wool to determine its correctness.

4. **Conclusion**:
- The correct statements are A and C. Therefore, wool keeps us warm in winter because it is an insulator and it traps air.

### Final Answer:
The correct answer is **A and C**: Wool is an insulator and wool traps air.