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': 'At what age does calcification of the primary dentition begin? \nSelect and explain. \nA. 6-10 weeks in utero, B. 13-16 weeks in utero, C. 22-26 weeks in utero, D. 30-34 weeks in utero', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]