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': 'First evidence of calcification of maxillary permanent central incisors occurs at: \nSelect and explain. \nA. 3-4 months, B. 10-12 months, C. 2-3 years, D. 3-4 years', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]