Assertion :- RNA is less stable then DNA.
Reason : In RNA'2 - OH group present on every nucleotide.

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 "RNA is less stable than DNA." This is a true statement. RNA (Ribonucleic Acid) is indeed less stable compared to DNA (Deoxyribonucleic Acid).

2. **Understanding the Reason**: The reason provided is "In RNA, a 2'-OH group is present on every nucleotide." This statement is also true. RNA contains ribose sugar, which has a hydroxyl (OH) group attached to the second carbon atom of the sugar molecule.

3. **Explaining the Stability**: The presence of the 2'-OH group in RNA makes it more reactive and less stable than DNA. DNA, on the other hand, has deoxyribose sugar, which lacks the 2'-OH group (it has only a hydrogen atom at that position). This absence of the 2'-OH group in DNA contributes to its greater stability.

4. **Conclusion**: Since both the assertion and the reason are true, and the reason correctly explains why RNA is less stable than DNA, we conclude that both statements are correct and the reason is the correct explanation for the assertion.

5. **Final Answer**: Therefore, the correct option is that both the assertion and reason are true, and the reason is the correct explanation for the assertion.