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: ENT
[{'content': 'Most common sinus to be involved in acute sinusitis? \nSelect and explain. \nA. Ethmoid, B. Maxillary, C. Sphenoid, D. Frontal', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Maxillary Most common sinus affected by sinusitis overall Maxillary Most common sinus affected in adult Maxillary Most common sinus affected in children Ethmoid Least common sinus affected Sphenoid Sinuses involved in order of frequency Maxillary > Frontal > Ethmoid > Sphenoid", 'role': 'assistant'}]