Which Statement Regarding the Common Amino Acids Found in Human $\alpha$

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

A) The $\alpha$ -carbon is bonded to one of 20 different R groups.
B) All of the amino acids have side groups that contain 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 of the $\alpha$ -amino acids are have polar functional groups.