Certain Amino Acids Are Essential to the Diet of Animals

Certain amino acids are essential to the diet of animals because they

A) prevent overnourishment.
B) are cofactors and coenzymes that are required for normal physiological function.
C) cannot be directly synthesized by animals through the transfer of an amino group to an appropriate carbon skeleton.
D) are needed to make stored fats that are used during hibernation and migration.
E) are the most important source of stored energy.