This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
Which one of the following drugs is most likely to block K+ channels in the heart responsible for the delayed rectifier current? 
Select and explain. 
A. Amiodarone, B. Encainide, C. Lidocaine, D. Phenytoin
A: Amiodarone
Answer: A: Amiodarone 
Explanation: Amiodarone is a highly effective antiarrhythmic drug, in part because of its multiple actions, which include Na channel block, beta adrenoceptor block, K channel block, and Ca channel block. Drugs that block K channels (which include class IA and class III antiarrhythmics) prolong APD and ERP and predispose toward torsades de pointes ventricular arrhythmias. Encainide is a class IC drug, lidocaine and phenytoin are class IB, and verapamil is class IV, none of which inhibits the delayed rectifier K current responsible for membrane repolarization during the cardiac action potential.