Assertion :- In lac operon, in the presence of inducer RNA polymerase access to the promotor and transcription proceeds.
Reason:- In lac operon in the presence of inducer repressor protein is inactivated

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we need to analyze the assertion and the reason provided regarding the lac operon.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "In lac operon, in the presence of inducer RNA polymerase access to the promoter and transcription proceeds."
- This is true because when an inducer (like lactose) is present, it binds to the repressor protein, causing a conformational change that prevents the repressor from binding to the operator region. This allows RNA polymerase to access the promoter and initiate transcription.

2. **Understanding the Reason**:
- The reason states that "In lac operon in the presence of inducer repressor protein is inactivated."
- This is also true. The presence of the inducer (lactose) leads to the inactivation of the repressor protein, which is crucial for allowing transcription to occur.

3. **Connecting Assertion and Reason**:
- The reason explains why the assertion is true. The inactivation of the repressor protein by the inducer is what allows RNA polymerase to access the promoter and proceed with transcription.

4. **Conclusion**:
- Both the assertion and the reason are true, and the reason correctly explains the assertion. Therefore, the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

### Final Answer:
- The correct answer is: **Both assertion and reason are true, and the reason is the correct explanation of the assertion.**