At the Local Zoo,a Polar Bear Suffered a Broken Tooth,and

Multiple Choice

At the local zoo,a polar bear suffered a broken tooth,and keepers needed a safe way of treating the problem.The bear was rewarded first for sticking its nose through a slot in the cage door,then for allowing a keeper to lift its lip and touch its teeth.Finally,a veterinarian was able to treat the damaged tooth while the bear waited placidly for its familiar reward.This is an example of

A) modelling.
B) shaping.
C) negative reinforcement.
D) secondary learning.