This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Adverse Drug Effect, Subject name: Pharmacology
[{'content': 'Eye defect by anti Tb drug: \nSelect and explain. \nA. Ethambutol, B. Pyrazinamide, C. Rifampicin, D. Isoniazid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. a. EthambutolRef: Goodman Gilman 13th E/P1074Reversible eye defect in the form of optic neuritis and red-green (green>red) colour blindness can be seen with ethambutol.Hence ophthalmological examination for same is mandatory.These intensity of ocular toxicities are both dose and duration dependent.', 'role': 'assistant'}]