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
Which of the following drug is a long acting beta–2 agonist ? 
Select and explain. 
A. Albuterol, B. Salmeterol, C. Pirbuterol, D. Orciprenaline
B: Salmeterol
Answer: B: Salmeterol 
Explanation: None