Correct Answer: A
Explanation:
(a): Nucleosides are condensation product of a pentose sugar and nitrogen base. Nucleotides are phosphorylated nucleosides with are formed by condensation of pentose, sugar, nitrogen base and at least one phosphoric residue. When nucleotides possess more than one phosphate radical, it is called higher nucleotides e.g. ATP.
ATP is a nucleotide as it is composed of adenine, ribose sugar and phosphoric acid. There are two additional phosphate groups attached to the phosphate group of AMP. The last two phosphate molecules are connected by high energy bonds.