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: Medicine
[{'content': 'The drug of choice in patients with Wolff-Parkinson-White syndrome with atrial fibrillation is \nSelect and explain. \nA. Digitalis, B. Procainamide, C. Verapamil, D. Adenosine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]