This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, 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: ref; KD Tripathi Pharmacology 7th edition(page no;223) Salmeterol is the first long-acting selective beta 2 agonist with a slow onset of action; used by inhalation on a twice-daily schedule for maintenance therapy and for nocturnal asthma, but not for acute symptoms. salbutamol can be used for acute symptoms