Answer:
4.) All are examples of using classical conditioning.
Explanation:
Actually, all options are using classical conditioning.
Classical conditioning is a learning procedure involving different stimulus. Ivan Pavlov was a Russian psychologist who experimented with classical conditioning using dogs. He taught them to associate a bell sound to being fed. In this context, the potent stimulus is the food, the neutral stimulus is the bell and the response is the salivation. Later in the experiment, the simple bell sound made dogs salivate, without even seeing or smelling food.
Therefore, to use classical conditioning, a stimulus is need, which all the answers have.
