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': 'Ethambutol causes : \nSelect and explain. \nA. Retrobulbar neuritis, B. Deafness, C. Red urine, D. Peripheral neuritis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ethambutol causes retrobulbar neuritis and can result in red-green colour blindness.', 'role': 'assistant'}]