Right option is (b) twenty
The best explanation: Both of these groups are linked to a central carbon (Cα), which is attached to hydrogen and a side chain group (R). Amino acids differ only by the side chain R group. The chemical reactivities of the R groups determine the specific properties of the amino acids. Amino acids can be grouped into several categories based on the chemical and physical properties of the side chains, such as size and affinity for water.
