This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
P wave is absent 
Select and explain. 
A. Atrial fibrillation, B. CCF, C. Atrial flutter, D. PSVT
A: Atrial fibrillation
Answer: A: Atrial fibrillation 
Explanation: Ans. (a) Atrial fibrillationRef: Ganong, 25th ed/p.524P wave is absent in atrial fibrillationInstead of p waves, only fibrillatory f waves are seenP wave is absent also in hyperkalemia