Assertion :- Tylor and colleages in 1958 used CsCl density gradient centrifugation technique to prove semiconservatie DNA replication.
Reason : They use `""^(15)N` heavy nitrogen which is not a radioactive isotope.

Options

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

Answer

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 Taylor and colleagues in 1958 used the CsCl density gradient centrifugation technique to prove semi-conservative DNA replication.
- However, it is important to note that the experiment that demonstrated semi-conservative DNA replication was actually conducted by Meselson and Stahl, not Taylor and colleagues. Therefore, the assertion is incorrect.

2. **Understanding the Reason**:
- The reason states that they used \(^{15}N\) heavy nitrogen, which is not a radioactive isotope.
- In reality, \(^{15}N\) is indeed a heavy isotope of nitrogen, but it is not radioactive. It is stable and is used in experiments to trace the incorporation of nitrogen into DNA. However, the statement that it is not radioactive is true, but it does not support the assertion correctly since the assertion itself is false.

3. **Conclusion**:
- Since both the assertion and the reason are incorrect, the correct answer is that both the assertion and reason are false.

### Final Answer:
Both assertion and reason are false.