Assertion : A transistor amplifier in common emitter configuration has a low input impedence.
Reason : The base to emitter region is forward biased.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are truw but reason is not 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 a transistor amplifier in common emitter (CE) configuration has a low input impedance.
- In a CE configuration, the input impedance is indeed low compared to other configurations (like common base or common collector).

2. **Understanding Input Impedance**:
- Input impedance (Z_in) is defined as the ratio of the change in voltage across the input terminals (V_be) to the change in input current (I_be).
- Mathematically, it is expressed as:
\[ Z_{in} = \frac{\Delta V_{be}}{\Delta I_{be}} \quad \text{(keeping V_ce constant)} \]
- Since the base current (I_be) is very small (in microamperes), the input impedance will also be low.

3. **Understanding the Reason**:
- The reason states that the base to emitter region is forward biased.
- In a common emitter configuration, the base-emitter junction is indeed forward biased, which allows current to flow into the base, thus enabling the transistor to operate as an amplifier.

4. **Linking Assertion and Reason**:
- While both the assertion and reason are true, the reason does not directly explain why the input impedance is low.
- The low input impedance is primarily due to the small base current, not just because the base-emitter junction is forward biased.

5. **Conclusion**:
- Both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion. Therefore, the correct answer is that both statements are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
- **Option B**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.