When a Parent Herring Gull Arrives at the Nest with Food,a

When a parent herring gull arrives at the nest with food,a chick will orient to and peck at the red spot on the parent's bill.The parent will then regurgitate the food into the chick's open mouth and the chick swallows it.What is this set of behaviors an example of?

A) sign stimulus
B) fixed action pattern
C) innate releasing mechanism
D) taxis
E) stimulus-response chain