Assertion: The distance between the parallel plates of a capacitor is halved, then its capacitance is doubled.
Reason: The capacitance depends on the introduced dielectric.

Options

A. If both assertion and reason are ture and reason is the correct explanation of assertion.
B. If both assertin and reason are ture but reason is not the correct explanation of assertion .
C. If assertion is true but 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 if the distance between the parallel plates of a capacitor is halved, then its capacitance is doubled.
- We know that the capacitance \( C \) of a parallel plate capacitor is given by the formula:
\[ C = \frac{A \cdot k \cdot \epsilon_0}{D} \]
where:
- \( A \) = area of the plates
- \( k \) = dielectric constant
- \( \epsilon_0 \) = permittivity of free space
- \( D \) = distance between the plates

2. **Calculating New Capacitance**:
- If the distance \( D \) is halved, the new distance becomes \( D/2 \).
- The new capacitance \( C' \) can be expressed as:
\[ C' = \frac{A \cdot k \cdot \epsilon_0}{D/2} = \frac{2A \cdot k \cdot \epsilon_0}{D} = 2C \]
- This shows that the new capacitance \( C' \) is indeed double the original capacitance \( C \).

3. **Understanding the Reason**:
- The reason states that the capacitance depends on the introduced dielectric.
- This is true because the dielectric constant \( k \) affects the capacitance. The presence of a dielectric material increases the capacitance of the capacitor.

4. **Conclusion**:
- Both the assertion and the reason are true.
- However, the reason provided does not directly explain why halving the distance results in doubling the capacitance. The assertion is based on the geometric relationship of the capacitor, while the reason pertains to the effect of dielectrics.
- Therefore, the assertion is true, the reason is true, but the reason is not the correct explanation of the assertion.

### Final Answer:
- The assertion is true, the reason is true, but the reason is not the correct explanation of the assertion.