Sphenoid sinus drains into?

Ans. A. Sphenoethmoidal recessThe lateral wall of nasal cavity presents three medial projections called conchae, which overlies meatuses. The sphenoethmoidal recess, above and posterior to the superior concha, receives the opening of the sphenoidal sinus. The superior meatus, under cover of the superior concha, receives the openings of the posterior ethmoidal cells. The middle meatus receives the opening of maxillary, frontal, anterior ethmoidal and posterior ethmoidal sinuses. The inferior meatus receives the opening of nasolacrimal duct.