The same hormone has considerably different effects in different species.The hormone thyroxine in humans stimulates metabolism,but in frogs it induces metamorphosis from tadpole to adult frog.This indicates that

A)the target tissues have evolved different responses.
B)metamorphosis is caused by a change in body metabolism.
C)the organisms have absolutely no evolutionary relationship.
D)the chemical composition of the hormone is actually slightly different.
E)the origin of the hormone makes a difference in the effect the hormone has on target tissues.