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: Ophthalmology
[{'content': 'In the nasolacrimal duct, valve of Hasner is present at its: \nSelect and explain. \nA. Upper end, B. Lower end, C. Middle, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Lower end', 'role': 'assistant'}]