Animals Require Certain Amino Acids in Their Diet

Animals require certain amino acids in their diet. An amino acid that is referred to as nonessential would be best described as one that

A) can be made by the animal's body from other substances.
B) is not used by the animal in biosynthesis.
C) must be ingested in the diet.
D) is less important than an essential amino acid.
E) is not found in many proteins.