The correct response is:
a single hydrogen atom, an amino group, and a carboxyl group
All amino acids share a common structure that includes a central carbon atom (the alpha carbon) to which a single hydrogen atom, an amino group (-NHâ‚‚), and a carboxyl group (-COOH) are attached. The only variable among different amino acids is the R group (or side chain), which differs from one amino acid to another.