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
[{'content': 'Purpose of the post treatment retention of an orthodontic case is: \nSelect and explain. \nA. To allow bony changes, B. To prevent tongue thrusting, C. To encourage the space closure, D. To Let the patient get used to the new functional position of the teeth', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]