Assertion (A): Adenine cannot pair with cytosine.
Reason (R): Adenine specifically forms hydrogen bonds with guanine whereas cytosine forms hydrogen bond with thymine.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. (A) is true but (R) is false.
4. Both (A) and (R) are false.