Answer: C
An amino acid has a central carbon atom surrounded by a hydrogen atom, a carboxyl group (-COOH) , an amino group(-NH2) and an alkyl group(-R). Hence if an a molecule has a singlt hydrogen atom which is bonded to a central carbon atom, an amino group and a carboxyl group both bonded to the same carbon atom, a R group which is also attached to the central carbon atom, the molecule is an amino acid(a monomer).
