This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
P wave is absent in 
Select and explain. 
A. Atrial fibrillation, B. CCF, C. Atrial flutter, D. PSVT
A: Atrial fibrillation
Answer: A: Atrial fibrillation 
Explanation: It is characterized by totally irregular and rapid rateThere are no recognizable P waveRef: Medical Physiology for Under Graduate students Indu Khurana 2015 pg no: 202