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
[{'content': 'Class II antiarrhythmics are - \nSelect and explain. \nA. Na+ channel blocker, B. K+ Channel opner, C. Beta-blocker, D. Calcium channel blocker', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Beta blocker Vaughan - williams classificationClass I Class II Class III Class IVNa+ channel blockerb - blockerK+ channel blockerCalcium channel blockers", 'role': 'assistant'}]