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': 'Minimum vision loss with which cataract: \nSelect and explain. \nA. Blue dot cataract, B. Zonular cataract, C. Anterior polar cataract, D. Posterior polar cataract', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Blue dot cataract', 'role': 'assistant'}]