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': 'The fastest acting cycloplegic drug is: \nSelect and explain. \nA. Atropine, B. Tropicamide, C. Cyclopentolate, D. Homatropine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Tropicamide', 'role': 'assistant'}]