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
Selective beta 2 blocker is ? 
Select and explain. 
A. Butoxamine, B. Betoxolol, C. Esmolol, D. Bisoprolol
A: Butoxamine
Answer: A: Butoxamine 
Explanation: Ans. is 'a' i.e., Butoxamine