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': 'Orange - skin cornea is due to \nSelect and explain. \nA. Siderosis, B. Chalcosis, C. Mustard gas, D. Lindane', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Mustard gas is Dichloroethyl sulphide causes orange skin cornea.', 'role': 'assistant'}]