The Hormone Prolactin,found in Distantly Related Vertebrates,exerts Different Effects in Different

The hormone prolactin,found in distantly related vertebrates,exerts different effects in different species.From an evolutionary standpoint,this is an indication that prolactin

A) is an ancient hormone whose function diversified through evolution.
B) was not required in fish and amphibians.
C) was a recent evolutionary adaptation.
D) can only have functions related to childbirth.