This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Asthma, Subject name: Pharmacology
[{'content': 'Which of the following is a long acting beta 2 agonist? \nSelect and explain. \nA. Salbutamol, B. Salmeterol, C. Terbutaline, D. Levalbuterol', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) SalmeterolRef.: KDT 6thed /127, 128', 'role': 'assistant'}]