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': "Which drug causes bull's eye macula: \nSelect and explain. \nA. Phenytoin, B. Chloroquine, C. Steroids, D. Ethambutal", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Chloroquine', 'role': 'assistant'}]