<prompt> QRS complex is due to -Ventricular repolarizationAtrial depolarizationConduction through AV nodeVentricular depolarization  <response>: Ans. is d i.e., Ventricular depolarization Event of ECGCauseP-waveAtrial depolarizationQRS complexVentricular depolarizationTwaveVentricular repolarizationPR intervalRepresents time taken by impulse to travel from SA node to ventricle Atrial depolarization and AV conductionQT intervalDuration of full ventricular contraction Ventricular depolarization Repolarization 