Assertion: Guanine cannot pair with cytosine.
Reason: Guanine and cytosine do not have perfect matching.

Options

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

Answer

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "Guanine cannot pair with cytosine." In the context of molecular biology, this is a claim about the base pairing rules in DNA.

2. **Understanding the Reason**: The reason provided is that "Guanine and cytosine do not have perfect matching." This suggests that there is an implication that the pairing is not suitable or correct.

3. **Base Pairing Rules**: In DNA, the base pairing rules dictate that guanine (a purine) pairs with cytosine (a pyrimidine) through hydrogen bonds. Specifically, guanine pairs with cytosine via three hydrogen bonds.

4. **Evaluating the Assertion**: Since guanine does indeed pair with cytosine in DNA, the assertion that "guanine cannot pair with cytosine" is false.

5. **Evaluating the Reason**: The reason states that guanine and cytosine do not have perfect matching. However, they do form a stable base pair through three hydrogen bonds, which is considered a strong and effective pairing. Therefore, this statement is also false.

6. **Conclusion**: Both the assertion and the reason are false.

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

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