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': 'Congenital obstruction of the lacrimal drainage system usually occurs at \nSelect and explain. \nA. Common canaliculus, B. Lacrimal sac, C. Valve of Hasner, D. Valve of Rosen muller', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Value of Hasner is at the opening of NLd into inferior meatus.', 'role': 'assistant'}]