Assertion: The resistance of a conductor increases with an increase in temperature.
Reason: While experimenting, a jockey is touched gently on a wire and it should not be pressed hard.

Options

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

Answer

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

**Assertion:** The resistance of a conductor increases with an increase in temperature.

**Reason:** While experimenting, a jockey is touched gently on a wire and it should not be pressed hard.

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The assertion states that the resistance of a conductor increases with an increase in temperature. This is a well-established principle in physics. As the temperature of a conductor increases, the kinetic energy of the charge carriers (electrons) also increases, leading to more frequent collisions with the lattice ions of the conductor. This results in an increase in resistance.

2. **Analyzing the Reason:**
- The reason provided talks about the proper technique of using a jockey in experiments, particularly in the context of a potentiometer or meter bridge. It states that the jockey should be touched gently and not pressed hard. This is important to avoid altering the cross-sectional area of the conductor, which would affect the resistance.

3. **Connecting Assertion and Reason:**
- While both the assertion and reason are correct statements in their own contexts, they do not directly explain each other. The assertion is about the relationship between temperature and resistance, while the reason is about the proper technique in an experimental setup. Therefore, the reason does not serve as an explanation for the assertion.

4. **Conclusion:**
- The assertion is true, and the reason is also true, but the reason does not explain the assertion. Thus, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
- **Assertion is true. Reason is true but does not explain the assertion.**