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
Location of rest in RPI or RPA system is: 
Select and explain. 
A. Mesial, B. Distal, C. Either of the above, D. None of the above
A: Mesial
Answer: A: Mesial 
Explanation: None