This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nose and paranasal sinuses, Subject name: ENT
[{'content': 'The maxillary sinus open intlo middle meatus at the level of: \nSelect and explain. \nA. Hiatus semilunaris, B. Bulla ethmoidalis, C. Infundibulum, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ref: Dhingra 7e pg 151,209.', 'role': 'assistant'}]