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': 'Maxillary sinus achieves maximum size at \nSelect and explain. \nA. bih, B. Primary dentition, C. At secondary dentition, D. At pubey', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Maxillary sinus is the first sinus to develop at bih. It is completely developed by 9 years of agei.e approximately at secondary dentition Ref Maqbool 11/e,p148.', 'role': 'assistant'}]