This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Arrhythmic, Subject name: Pharmacology
Class II antiarrhythmics are - 
Select and explain. 
A. Na+ channel blocker, B. K+ Channel opner, C. Beta-blocker, D. Calcium channel blocker
C: Beta-blocker
Answer: C: Beta-blocker 
Explanation: Ans. is 'c' i.e., Beta blocker Vaughan - williams classificationClass I Class II Class III Class IVNa+ channel blockerb - blockerK+ channel blockerCalcium channel blockers