This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Acquired Cataract, Subject name: Ophthalmology
[{'content': 'Chalcosis is caused by? \nSelect and explain. \nA. Iron, B. Lead, C. Copper, D. Mercury', 'role': 'user'}, {'content': 'Answer: C \nExplanation: ANSWER: (C) CopperREF: Khurana 4th ed p. 493"Chalcosis refers to specific changes made by copper containing alloys in eye"Features of chalcosis are:[?] KF rings on descement membrane of cornea [?] Sunflower cataract[?] Golden brown metallic sheen plaques on the retinal pole', 'role': 'assistant'}]