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': 'Paranasal sinus opening in middle meatus: \nSelect and explain. \nA. maxillary, B. Anterior ethmoid, C. Posterior ethmoid, D. Frontal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Anterior group of paranasal sinus which includes maxillary, frontal and anterior ethmoidal. They all open in the middle meatus and their ostia lie anterior to basal lamella of middle turbinate Ref: Dhingra 7e pg 209.', 'role': 'assistant'}]