Adenine is a

Purines and pyrimidines are nitrogenous bases.

Adenine and guanine are the purines.

Thymine and cytosine are pyrimidines.

Purines have a double ring structure, whereas pyrimidines have a single ring composed of carbon and nitrogen.

Purines form hydrogen bonds with pyrimidines.

C₅H₅N₅ is the molecular formula.

Final Answer:

Hence, the correct answer is option (A) i.e., Purine