A conditioned stimulus is repeatedly presented and always followed by an unconditioned stimulus. Will the animal necessarily develop a conditioned response? Why or why not? 

A. It depends. The animal may or may not develop a conditioned response, depending on whether or not the CS is similar to the UCS. 

B. It depends. The animal may or may not develop a conditioned response, depending on whether or not the species is biologically prepared to develop that type of association. 

C. Yes, the animal must develop a conditioned response because of the principle of temporal contiguity. 

D. Yes, the animal must develop a conditioned response because of the principle of spontaneous recovery.