Answer:
Conditioned stimulus
Explanation:
In the classical conditioned, these terms such as condition stimulus, UCS, CS, NS, etc are being used to modify the behavior of a person, animal, etc. The conditioned stimulus is neutral before as a conditioned stimulus. Ivan Pavlov was the first psychologist who has been used classical conditioning in which a person used CS, UCS, UCR, and CR.
Thus here in the above statement, the person eats a hamburger. Before used it, it was a neutral stimulus but after using it, it becomes a conditioned stimulus.
