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
Which of the following is long acting sympatho mimetics used in Bronchial asthma 
Select and explain. 
A. Salbutamol, B. Terbutaline, C. Bamboterol, D. Salmetrol
D: Salmetrol
Answer: D: Salmetrol 
Explanation: (Salmetrol) (218-KDT 6th)Salmetrol - It is first -long acting selective b2 agonist with slow onset of action* It is also more b2 selective and lipophilic than salbutamolFormoterol - another long acting selective b2 agonists has faster onset of action