Plzzzzzz reply as soon as possible this question belongs to molecular basis of inheritance

For Answering this you should be familiar with CHARGAFF’s rule.

DNA has four distinct nitrogenous bases: two purines (adenine and guanine) and two pyrimidines (thymine and cytosine). Adenine bonds with thymine, and guanine bonds with cytosine. Therefore, for each adenine, there must be a thymine to pair with it. Similarly for each cytosine, there must be guanine to pair with it.
% A = % T and % G = % C

Solution: If cytosine is 18% then Guanine should also be 18%.
C+G= 36%
A+T= 100% – 36%
A+T= 64%
A = 64/2= 32%

so answer is A= 32%