Assertion : Lac operon is a repressible operon.
Reason : The product of gene activity stops the activity of the said gene.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true 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

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "Lac operon is a repressible operon." To evaluate this, we need to understand what a repressible operon is. A repressible operon is typically one that is usually active but can be turned off (repressed) in the presence of a specific substance.

2. **Understanding the Lac Operon**: The lac operon is a well-studied example in molecular biology. It is primarily involved in the metabolism of lactose in bacteria, particularly E. coli. The lac operon is known to be an inducible operon, meaning it is usually off but can be turned on (induced) when lactose is present.

3. **Evaluating the Reason**: The reason states that "The product of gene activity stops the activity of the said gene." This statement implies that the gene product acts as a repressor. In the case of the lac operon, when lactose is present, it binds to the repressor protein, causing it to release from the operator region, thus allowing transcription to occur. Therefore, the product of the gene activity does not stop the activity of the gene; rather, it allows for the gene expression when lactose is present.

4. **Conclusion**: Since the assertion that the lac operon is a repressible operon is incorrect (it is an inducible operon), and the reason given is also incorrect (the product of the gene activity does not stop the activity of the gene), we conclude that both the assertion and the reason are false.

5. **Final Answer**: Both the assertion and the reason are false.