Assertion. Constitutive genes are also known as house keeping genes
Reason. Constitutive genes fail to express, as their products are not required for essential normal activities.

Options

A. If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion .
B. If both Assertion and Reason are true but Reason is not a correct explanations of the Assertion
C. If Assertion is true but the Reason is false .
D. If both Assertion and Reason are false.

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "Constitutive genes are also known as housekeeping genes." This is true. Constitutive genes are those that are continuously expressed in all cells because they are necessary for basic cellular functions.

2. **Understanding the Reason**: The reason given is "Constitutive genes fail to express, as their products are not required for essential normal activities." This statement is false. Constitutive genes are always expressed because their products (like proteins) are essential for normal cellular activities.

3. **Evaluating the Relationship**: Since the assertion is true and the reason is false, we can conclude that the assertion stands independently of the reason provided.

4. **Final Conclusion**: The correct answer is that the assertion is true, but the reason is false.