This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ECG and Arrhythmia 2, Subject name: Medicine
[{'content': 'Which is the most common benign cardiac rhythm? \nSelect and explain. \nA. Atrial premature contraction, B. Atrial fibrillation, C. Ventricular premature contraction, D. Ventricular tachycardia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Atrial premature contraction mc benign rhythm during extended ECG monitoring. Asymptomatic, although some patients experience palpitations or an irregularity of the pulse. ECG -Identification of P wave that occurs before the anticipated sinus beat.', 'role': 'assistant'}]