The essential amino acids?

(A) Must be supplied in the diet because the
organism has lost the capacity to aminate the
corresponding ketoacids
(B) Must be supplied in the diet because the
human has an impaired ability to synthesize
the carbon chain of the corresponding ketoacids
(C) Are identical in all species studied
(D) Are defined as those amino acids which
cannot be synthesized by the organism at a
rate adequate to meet metabolic requirements