Which of the Following Is True Regarding The $\alpha$ -Carbon of an Amino Acid?
A)there Are Always Four Different

Multiple Choice

Which of the following is true regarding the $\alpha$ -carbon of an amino acid?

A) there are always four different functional groups attached
B) the most commonly occurring form of amino acids are the D-amino acids
C) when assigning the R-S stereochemistry, the carboxylic acid is always the highest priority functional group
D) for all amino acids except glycine, the $\alpha$ -carbon is a stereocenter
E) none of the above