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
Which is the most common benign cardiac rhythm? 
Select and explain. 
A. Atrial premature contraction, B. Atrial fibrillation, C. Ventricular premature contraction, D. Ventricular tachycardia
A: Atrial premature contraction
Answer: A: Atrial premature contraction 
Explanation: 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.