You Train Your Dog, Milo, to Salivate at the Sound

You train your dog, Milo, to salivate at the sound of a bell. Then you ring the bell every five minutes and don't follow the ringing with food for Milo. He salivates less and less and finally stops salivating at all when the bell rings. But the next morning, when you ring the bell, Milo salivates! What term is used to explain the reappearance of this response?

A) counterconditioning
B) instinctive drift
C) spontaneous recovery
D) stimulus discrimination