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
New odontoblasts are differentiated from mesenchymal cells in: 
Select and explain. 
A. 1 week, B. 2 week, C. 4-6 weeks, D. 1 month
B: 2 week
Answer: B: 2 week 
Explanation: In about 15 days new odontoblasts are differentiated from mesenchymal cells of the pulp and these odontoblasts lay down the reparative dentin.