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 initiation of primary dentition is\nusually around: \nSelect and explain. \nA. 4 months in utero, B. Birth, C. 4 months after birth, D. One year after birth', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]