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
The average diameter of coronal dentinal tubules near the pulp is: 
Select and explain. 
A. 0.2-0.5 microns, B. 2-3 microns, C. 0.2-0.3 microns, D. 7 microns
B: 2-3 microns
Answer: B: 2-3 microns 
Explanation: None