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': 'Toxic amblyopia is produced by: \nSelect and explain. \nA. INH, B. Rifampicin, C. Ethambutol, D. Pyrazinamide', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Rifampicin', 'role': 'assistant'}]