This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
QRS complex is due to: September 2008 
Select and explain. 
A. Ventricular repolarization, B. Atrial depolarization, C. Conduction through AV node, D. Ventricular depolarization
D: Ventricular depolarization
Answer: D: Ventricular depolarization 
Explanation: Ans. D: Ventricular depolarizationQRS complex is due to ventricular depolarization and atrial repolarization. Normal duration is 0.08 sec.