Fred's Dog Was Classically Conditioned to Salivate at the Sound

Multiple Choice

Fred's dog was classically conditioned to salivate at the sound of a bell. Fred then repeatedly paired the bell with another stimulus, a whistle. Now whenever he blows the whistle, his dog salivates, even though the whistle has never been paired with food. This example illustrates:

A) higher order conditioning (second-order conditioning) .
B) spontaneous recovery.
C) a placebo response.
D) biological preparedness.