Assertion :- DNA is chemically and structural more stable.
Reason : In DNA thymine is present instead of uracil.

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

**Step-by-Step Solution:**

1. **Understanding the Assertion:**
- The assertion states that "DNA is chemically and structurally more stable."
- This is true because DNA has a double-helix structure and the presence of deoxyribose sugar makes it less reactive compared to RNA.

2. **Understanding the Reason:**
- The reason provided is "In DNA, thymine is present instead of uracil."
- This statement is also true. DNA contains thymine (T) while RNA contains uracil (U).

3. **Linking the Reason to the Assertion:**
- The presence of thymine instead of uracil contributes to the stability of DNA.
- Thymine is more resistant to photochemical reactions and mutations compared to uracil, which helps in maintaining the integrity of the genetic information.

4. **Conclusion:**
- Since both the assertion and the reason are true, and the reason explains why the assertion is true, we can conclude that the correct answer is that both statements are true and the reason is the correct explanation for the assertion.

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

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