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': 'Lip bumper not used in the treatment of \nSelect and explain. \nA. Lip biting, B. Distalisation of molars, C. Nail biting, D. Lip exercises', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]