The Utilization of Ammonia for Synthesis of the Alpha-Amino Group

The utilization of ammonia for synthesis of the alpha-amino group of non-essential amino acids is

A) dependent upon the action of glutamate dehydrogenase.
B) achieved by reversal of the urea cycle.
C) mediated by carbamoyl phosphate.
D) effected through the intermediate of carbamino acids.
E) dependent upon the intestinal bacterial flora.