This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
[{'content': 'What is deposited in Kyser-FIeischer ring - \nSelect and explain. \nA. Copper, B. Lead, C. Mercury, D. Heme', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., CopperKayser-FLeischer (KF) ring - Copper deposition in Chalcosis or Wilson's diseaseFleischer ring - Deposition of iron and is a sign of keratoconus", 'role': 'assistant'}]