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: Pharmacology
[{'content': 'Optic neuritis is caused by following, except: \nSelect and explain. \nA. Ethambutol, B. Chloroquine, C. Steroid therapy, D. Methanol', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Steroid therapy', 'role': 'assistant'}]