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': 'New odontoblasts are differentiated from mesenchymal cells in: \nSelect and explain. \nA. 1 week, B. 2 week, C. 4-6 weeks, D. 1 month', 'role': 'user'}, {'content': 'Answer: B \nExplanation: In about 15 days new odontoblasts are differentiated from mesenchymal cells of the pulp and these odontoblasts lay down the reparative dentin.', 'role': 'assistant'}]