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: Anatomy
Parotid duct opens at 
Select and explain. 
A. 1st PM, B. 1st molar, C. 2nd upper molar, D. 2nd lower molar
C: 2nd upper molar
Answer: C: 2nd upper molar 
Explanation: None