Which Statement Regarding Amino Acids Found in Human Proteins Is $\alpha$

Which statement regarding amino acids found in human proteins is NOT correct?

A) The $\alpha$ -carbon is bonded to one of 20 different R groups.
B) Nearly half of the amino acids have side groups containing only carbon and hydrogen.
C) Several of the amino acids have side groups containing the carboxylic acid functional group.
D) Several of the amino acids have weakly basic side groups that contain nitrogen.
E) All $\alpha$ -amino acids are nonpolar.