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': 'Most important side effect of ethambutol is : \nSelect and explain. \nA. Hepatotoxicity, B. Renal toxicity, C. Peripheral neuropathy, D. Retrobulbar neuritis', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]