Final answer:
Extinction in psychology refers to the weakening and eventual disappearance of a conditioned response when the conditioned stimulus is no longer paired with the unconditioned stimulus. The correct answer to the question is option b. conditioned stimulus.
Step-by-step explanation:
Extinction occurs when a conditioned stimulus is no longer paired with an unconditioned stimulus. In classical conditioning, this leads to a decrease in the conditioned response over time. For instance, if you ring a bell (a conditioned stimulus) before feeding a dog, the dog will eventually salivate upon hearing the bell due to the association of the bell with food (the unconditioned stimulus). If you continue to ring the bell but stop providing the food, the dog will gradually stop salivating to the sound of the bell. This process of unpairing the conditioned stimulus from the unconditioned stimulus is what causes the previously conditioned response to weaken and eventually disappear.
To answer the student's question: Extinction occurs when a(n) conditioned stimulus is no longer paired with an unconditioned stimulus. Therefore, the correct option is b. conditioned stimulus.