Dogs conditioned to salivate to stimulation of the thigh also begin to salivate when stimulated on other body parts. this best illustrates
a. generalization.
b. an unconditioned response.
c. spontaneous recovery.
d. an operant behavior.

a. generalization

Explanation:

In psychology and conditioning, the term generalization refers to the phenomenon that takes place when, after learning a behavior, a stimulus that is similar to the one that provoques the first answer, provoques the same answer.  In other words, the individual responds in the same way to similar stimulus.

In this example dogs are conditioned to salivate to stimulation of the thigh (the stimulus would be the stimulation of the thigh), however, this salivating conduct also takes place when they are stimulated on other body parts (which is a similar stimulus to the original one). Therefore they are responding in the same way, salivating, to similar stimulus. Therefore, this best illustrated generalization.