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': 'The lip is supported by \nSelect and explain. \nA. Relation of lip edge and facial surfaces of teeth, B. Labial sulcus between teeth and lip, C. Relationship of tongue and teeth, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]