The correct option is A Adenine, Guanine
DNA (deoxyribose nucleic acid) consists of 3 different molecules - phosphate, 5-carbon deoxyribose sugar and nitrogenous base. The nitrogenous base may be a 9-membered, double purine, i.e., adenine (A) or guanine (G), or a 6-membered, single -ringed pyrimidine, i.e., thymine (T) or cytosine (C).