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
Odontoblasts are derived from ____________ 
Select and explain. 
A. Undifferentiated mesenchymal cells, B. Histocytes, C. Macrophages, D. Lymphocytes
A: Undifferentiated mesenchymal cells
Answer: A: Undifferentiated mesenchymal cells 
Explanation: None