In pavlov's study, a dog salivates to the sound of a tone because the tone has been regularly associated with the delivery of food. in this case, the tone is called a(n):

In Pavlov's study, a dog salivates to the sound of a tone because the tone has been regularly associated with the delivery of food. in this case, the tone is called a conditioned stimulus.
The Russian scientist Pavlov showed that the dogs were demonstrating classical conditioning.
John Watson later showed that the same happens in humans.

3. i would say one, but one is not prime nor composite.