This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'True about sphenoid sinus - \nSelect and explain. \nA. Lined by stratified squamous epithelium, B. Duct open in middle meatus, C. Open in sphenoethmoid recess, D. Present at birth', 'role': 'user'}, {'content': 'Answer: C \nExplanation: All paranasal sinuses are lined by respiratory epithelium (i.e. ciliated pseudo stratified columnar epithilium) i.e. option a is incorrect.\n\nSphenoid sinus: Important points\n\nIt is not present at birth\nIt occupies the body of sphenoid\nOstrum of sphenoid sinus is situated in the upper part of anterior wall and drains into spheno ethmoidal recess.\nOn x ray: Sphenoid sinus is visible by 4 years of age.', 'role': 'assistant'}]