Explanation:
(a) Glycine is the simplest amino acid with lowest molecular weight. The side chain in glycine is represented by $\text{H}$ (Hydrogen) atom (not alkyl group). Due to 2-opposite $\text{H}$-atoms, this amino acid is symmetrical or achiral. All other amino acids are assymetrical or chiral, and can exist as D- and L-stereoisomers.