When Pavlov Was Conditioning His Dog to Salivate in Response

Multiple Choice

When Pavlov was conditioning his dog to salivate in response to a tone, he first paired the tone with the presentation of food until the tone alone could induce salivation. In his experiments, which of the following was considered to be the unconditioned stimulus?

A) the food
B) salivation in response to the food
C) salivation in response to the tone
D) the food and the tone
E) the tone