Amino acids can be distinguished from one another by:
a. the number of [tex]\mathrm{R}[/tex] groups found on the amino acid molecules
b. the type of bond between the [tex]\mathrm{R}[/tex] group and the rest of the amino acid molecule
c. the chemical properties of their [tex]\mathrm{R}[/tex] groups
d. the chemical properties of their amino and carboxyl groups