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: Surgery
Oro antral fistula most commonly occurs during extraction of: 
Select and explain. 
A. Maxillary 1st premolar, B. Maxillary 2nd premolar, C. Maxillary 1st molar, D. Maxillary 3rd molar
C: Maxillary 1st molar
Answer: C: Maxillary 1st molar 
Explanation: None