This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
The principle that 'the stimulus must be altered to elicit
a change in the response' is applied in 
Select and explain. 
A. Reinforcement, B. Aversive Conditioning, C. Retraining, D. Modeling
C: Retraining
Answer: C: Retraining 
Explanation: None