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
[{'content': 'Oro antral fistula most commonly occurs during extraction of: \nSelect and explain. \nA. Maxillary 1st premolar, B. Maxillary 2nd premolar, C. Maxillary 1st molar, D. Maxillary 3rd molar', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]