Stereoisomers Exist for Most of the Amino Acids Found in Nature

Stereoisomers exist for most of the amino acids found in nature. Which statement below is correct?

A) Both the D-amino acids and the L- amino acids are used by living things.
B) Only the L-amino acids are incorporated in proteins.
C) A common conversion is from the D-amino acid to the L-amino acid.
D) L-amino acids are toxic.