This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro-Ophthalmology, Subject name: Ophthalmology
[{'content': 'Which one of the following is an oculotoxic drug? \nSelect and explain. \nA. Isoniazid, B. Ethambutol, C. Streptomycin, D. Rifampin', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. (b) EthambutolRef: Parson's 22/e, p. 244, 366; Kanski 7/e, p. 868)Visual symptoms or toxic optic neuropathy occurs more commonly if dose exceeds 25 mg/kg/day. Patient experiences red-green colour blindness and blurring", 'role': 'assistant'}]