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 most common curvature of the palatal root of maxillary first molar is: 
Select and explain. 
A. Facial, B. Lingual, C. Distal, D. Mesial
A: Facial
Answer: A: Facial 
Explanation: None