Adenine is (A) Purine (B) Pyrimidine (C) Nucleoside (D) Nucleotide
The nitrogenous bases are purines and pyrimidines. The purines are adenine and guanine. The pyrimidines are thymine and cytosine. The purines are double ring structure while the pyrimidines are the single ring made up of carbon and nitrogen. Purines pair with the pyrimidines by hydrogen bonds. The molecular formula is C5H5N5. So, the correct answer is option A.
