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
Odontoblastic layer’s cell size: 
Select and explain. 
A. Directly depends on no. of dentinal tubules, B. Tall columnar in crown, C. Squamous in apical portion, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: None