The correct answer is letter A
Spontaneous recovery refers to the reappearance of the conditioned response after a rest period or less response period. If the conditioned stimulus is unconditioned it is not associated, an extinction.
For example, in Ivan Pavlov's classic experiment, dogs were conditioned to salivate at the sound of a bell. Pavlov also noted that failing to match the sound to the presentation of the food led to the extinction of the salivation response.
However, after a two-hour rest period, the salivation response suddenly reappeared when the bell sounded.
For another example, imagine that you used classic conditioning to train your dog to expect food whenever he hears the sound of a bell. When you ring the bell, your dog runs into the kitchen and searches for its food container. After the response has been conditioned, you stop presenting food after ringing the bell. Over time, the response becomes extinct, and your dog stops responding to the sound. You stop ringing the bell completely, but a few days later you decide to try to ring the bell again. Your dog runs into the room and waits for his bowl, showing a spontaneous recovery from the conditioned response.