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': 'Brown skin cornea is seen in -a) Siderosisb) Mustard gas exposurec) Chalcosisd) Argyrosis \nSelect and explain. \nA. ac, B. bc, C. ad, D. b', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Brown discoloration of cornea may be seen in :-\n\n\nSiderosis (Iron deposition) \xa0 \xa0\xa0\nChalcosis (copper deposition) : KF rings \xa0 \xa0 \xa0 \xa0 \xa0\xa0\nDrugs : Phenothiazines vii) Kyrle disease\nChrysiasis (gold deposition)\nBlood staining\nBenzoquinone, hydroquinine\n\n\nArgyrosis (silver deposition) causes slate gray discoloration.\nI am not sure about option b', 'role': 'assistant'}]