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': 'Which is the shortest acting mydriatic ? \nSelect and explain. \nA. Atropine, B. Tropicamide, C. Cyclopentolate, D. Homatropine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Atropine is longest acting (5-6 days) whereas tropicamide\xa0is the shortest acting (15-60 min) mydriatic.', 'role': 'assistant'}]