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': 'Treatment of chronic dacrocystitis  a) Dacrocystorhinostomy     b) Antibiotics    c) Probing    d) Massage \nSelect and explain. \nA. abcd, B. abc, C. acd, D. bcd', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]