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: Anatomy
[{'content': "Location Hasner's of valve? \nSelect and explain. \nA. Opening of nasolacrimal duct, B. Sphenoidal sinus opening, C. Frontal sinus opening, D. Ethmoidal sinus opening", 'role': 'user'}, {'content': "Answer: A \nExplanation: Opening of nasolacrimal ductNasolacrimal duct opens into inferior meatus and is closed by a mucosal flap called Hasner's valve", 'role': 'assistant'}]