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
Number of tubules per unit area 
Select and explain. 
A. Is 2 times more at pulpal end, B. Is 3 times more at pulpal end, C. Is 4 times more at pulpal end, D. Is 5 times more at pulpal end
C: Is 4 times more at pulpal end
Answer: C: Is 4 times more at pulpal end 
Explanation: The number of tubules per unit area is more at the pulpal end by 4 times than at their terminal end. Hence the intertubular dentin is well appreciated at the terminal end. The tubules generally have a doubly convex course, the primary curvature (often called ―S‖ shaped tubules), the first convexity of which is directed towards apex.