This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Congenital Lesions and Stridor, Subject name: ENT
[{'content': 'Antral fistula is most common after extraction of: \nSelect and explain. \nA. 2nd incisor, B. 1st premolar, C. 3rd molar, D. 1st molar', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (d) 1st molar(Ref. Scott Brown, 6th ed., 1/5/25)The floor of the maxillary sinus is related to 2nd premolar and 1st molar. Therefore extraction of these teeth can lead to an oro-antral fistula.', 'role': 'assistant'}]