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': 'Cataract blindness is: \nSelect and explain. \nA. Preventable, B. Curable, C. Avoidable, D. Curable and avoidable', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Curable', 'role': 'assistant'}]