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 is a long acting β2 selective agonist ? \nSelect and explain. \nA. Formoterol, B. Isoprenaline, C. Salbutamol, D. Ephedrine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]