Carrie Fed Her Cat Canned Tuna Fish That Was Opened

Multiple Choice

Carrie fed her cat canned tuna fish that was opened with an electric can opener. Even when she was merely opening a can of corn, her cat responded physically as if it were about to be fed. In this example, the unconditioned stimulus is the

A) corn.
B) tuna fish
C) sound of the electric can opener.
D) eating behaviours.