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 sympathominetic agents is the most bronchodilator 
Select and explain. 
A. Amphetamine, B. Nor epinephrine, C. Isoproterenol, D. Phenylephrine
C: Isoproterenol
Answer: C: Isoproterenol 
Explanation: None