A Bird Breeder Feeds Her Hungry,chirping Chicks a Diet Formula

Multiple Choice

A bird breeder feeds her hungry,chirping chicks a diet formula after heating it in her microwave.After a few days,the chicks begin chirping when they hear the sounds of the buttons on the microwave being pushed.In this example,the conditional stimulus is the

A) taste of the formula.
B) hunger experienced by the birds.
C) chirping sound made by the chicks.
D) sounds of the microwave.
E) sense of satiation produced by the consumption of the formula.