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
True about sphenoid sinus: 
Select and explain. 
A. Lined by staified squamous epithelium, B. Duct open in middle meatus, C. Open in sphenoethmoid recess, D. Present at bih
C: Open in sphenoethmoid recess
Answer: C: Open in sphenoethmoid recess 
Explanation: All paranasal sinuses are lined by respiratory epitheliumi.e option a is incorrect. sphenoid sinus:Impoant points it is not present at bih it occupies the body of sphenoid ostrum of sphenoid sinus is situated in the upper pa of anterior wall and drains intlo spheno ethmoidal recess on x ray sphenoid sinus is visible by 4 years of age. Ref Dhingra 6/e,p 188