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
Pain originate in the pulp due to 
Select and explain. 
A. free nerve ending in cell rich zone, B. free nerve ending at sub odontoblastic layer, C. Krause bulb at the center of the pulp, D. Meisseners corpuscles at cell rich zone
B: free nerve ending at sub odontoblastic layer
Answer: B: free nerve ending at sub odontoblastic layer 
Explanation: None