This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lens, 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: In blue dont cataract, opacities are usually stationary and do not affect vision. Ref: Khurana 7th/e p.190&4th/e p.173.', 'role': 'assistant'}]