Assertion (A): During reverse, biasing a diode doesn't conduct current.
Reason (R) : It narrows the depletion layer.

Options

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

Explanation

To solve the given problem, we need to analyze both the assertion and the reason provided in the question regarding a diode during reverse biasing.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "During reverse biasing, a diode doesn't conduct current."
- In reverse bias, the p-type semiconductor is connected to the negative terminal of the battery, and the n-type semiconductor is connected to the positive terminal. This configuration creates an electric field that pulls the majority charge carriers (holes in p-type and electrons in n-type) away from the junction.

2. **Analyzing the Depletion Layer**:
- As the majority carriers are pulled away from the junction due to the applied electric field, the depletion layer (the region around the junction devoid of free charge carriers) widens. This is contrary to the assertion that the depletion layer narrows during reverse biasing.

3. **Understanding the Reason**:
- The reason states that "It narrows the depletion layer."
- However, as explained, during reverse biasing, the depletion layer actually widens because the majority carriers are being pulled away from the junction, leading to an increase in the width of the depletion region.

4. **Conclusion**:
- The assertion is true: a diode does not conduct current during reverse biasing.
- The reason is false: the depletion layer does not narrow; it widens during reverse biasing.

5. **Final Answer**:
- The correct option is that the assertion is true, and the reason is false.

### Summary:
- **Assertion (A)**: True
- **Reason (R)**: False