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 - 
Select and explain. 
A. Opposite 1st molar, B. Opposite 2nd molar, C. Into the papilla, D. Opposite incisor
B: Opposite 2nd molar
Answer: B: Opposite 2nd molar 
Explanation: Parotid duct opens opposite the 2nd upper molor tooth.