In Some Cases, a Single Amino Acid Substitution Can Cause

In some cases, a single amino acid substitution can cause a protein to lose its biological activity.In other cases, a single amino acid substitution causes no change to a protein's biological activity.Which statement can best be used as evidence to support an explanation for these observations?

A) Amino acids are covalently linked through peptide bonds to form the primary structure of a protein.
B) Amino acids found in the proteins of living organisms have many similarities, including an alpha-amino group and an alpha-carboxyl group.
C) Amino acids occur as optical isomers, but only one isomer of each is found in the proteins of most of the organisms on Earth.
D) Noncovalent interactions between atoms in a polypeptide chain stabilize the secondary, tertiary, and quaternary levels of its structure.
E) Each amino acid side chain has properties that are very different from those of some side chains and very similar to those of others.