This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': "Which of the following drugs can cause torsades'de pointers? \nSelect and explain. \nA. Quinidine, B. Lignocaine, C. Esmolol, D. Flecainide", 'role': 'user'}, {'content': 'Answer: A \nExplanation: class 1A agents, class 3 antiarrythymic agents commonly produce torsades de pointes class 1 a- quinidine, disopyramide, procainamide class 1b agents doesnt produce torsades pointes-eg lidocaine, phenytoin, mexiletine, tocainide flecainide is class 1c REF.Essentials of Pharmacology KD Tripathi 8th ed.', 'role': 'assistant'}]