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
Paranasal sinus opening in middle meatus: 
Select and explain. 
A. maxillary, B. Anterior ethmoid, C. Posterior ethmoid, D. Frontal
B: Anterior ethmoid
Answer: B: Anterior ethmoid 
Explanation: 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.