If Your Dog Was Classically Conditioned to Wag His Tail

Multiple Choice

If your dog was classically conditioned to wag his tail when you pick up a leash to go for a walk, what would extinguish this behavior?

A) taking him for a walk without his leash
B) repeatedly picking up the leash without taking him for a walk
C) using operant conditioning to teach him to recognize the word "walk"
D) Once learned, this behavior cannot be extinguished.