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: Medicine
[{'content': 'P wave is absent in- \nSelect and explain. \nA. Atrial fibrillation, B. Atrial asystole, C. Ventricular fibrillation, D. Ventricular tachycardia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Absence of the P wave with a flat baseline may indicate: Fine atrial fibrillation Sinoatrial arrest (with a secondary escape rhythm ) in ventricular fibrilation ,ventriculat tachycardia and atrial asystole,a waves are present Ref Harrison 20th edition pg 1423', 'role': 'assistant'}]