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': 'In how many years, the mandibular central incisors erupt as permanent teeth? \nSelect and explain. \nA. 8-9 years, B. 10-12 years, C. 6-7 years, D. 17-25 years', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]