Which Statement Concerning the Twenty Different α-Amino Acids Widely Found

Which statement concerning the twenty different α-amino acids widely found in nature is true?

A) Each α-amino acid has a different number of carbon atoms.
B) Each α-amino acid has one amino (−NH₂) group.
C) Each α-amino acid has one carboxylic acid (−COOH) group.
D) These α-amino acids differ in the R groups attached to the α-carbon.
E) None of these α-amino acids are aromatic compounds.