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 of the following drug is a long-acting beta-2-agonist? \nSelect and explain. \nA. Albuterol, B. Salmeterol, C. Pirbuterol, D. Orciprenaline', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Salmeterol Long acting beta-2-agonist. Whereas others are all sho-acting agents.', 'role': 'assistant'}]