The correct answer is A-III, B-II, C-I, D-IV - Adenosine - It is a nucleoside which is composed of nitrogen base and sugar only. - Adenylic acid - It is a nucleotide which is composed of nitrogen base, sugar and a phosphate group is esterified to the sugar. - Adenine - Nitrogen base (Purine) Alanine - An amino acid that contains a methyl group as the ' R ' group.