Amino Acids Are the Building Blocks of Proteins

Amino acids are the building blocks of proteins.Which of the following statements concerning amino acids is FALSE?

A) There are 20 different amino acids that occur naturally in human proteins.
B) The amino acids that make up human proteins are called essential amino acids.
C) The amino acids present in human proteins are "alpha" amino acids.
D) Except for glycine,where R=H,amino acids are chiral molecules.
E) Amino acids are classified by the nature of the side chain R groups that are present.