All drains into middle meatus except:: (A) lacrimal duct, (B) Maxillary sinus, (C) Frontal sinus, (D) Ethmoidal sinus
Answer is A. 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.