Answer:
The answer is spontaneous recovery.
Explanation:
Regarding theories of learning and conditioning, spontenous recovery is a term used to describe the sudden reappearance of a reponse that was believed to be extinct. It may occur even after a long time without any exposure to the stimulus (the geese in this example).
Spontaneous recovery demonstrates that an extinct response is not the same as an unlearned response. In other words, some behaviours may never be fully eliminated.