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
Method to modify the child's behaviour by the presentation or withdrawal of certain reinforcers is known as: 
Select and explain. 
A. Contingency management., B. HOME., C. Physical restraint., D. Retraining.
A: Contingency management.
Answer: A: Contingency management. 
Explanation: None