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': 'KF ring has deposition of which of the following in the Descemet’s membrane? \nSelect and explain. \nA. Copper, B. Arsenic, C. Iron, D. Mercury', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Kayser-Fleischer (KF) ring → Copper deposition in Chalcosis or Wilson’s disease Fleischer ring\n→ Deposition of iron and is a sign of keratoconus', 'role': 'assistant'}]