<prompt> QRS complex is due to?Ventricular repolarizationVentricular depolarizationAtrial repolarizationAtrial depolarization  <response>: QRS complex is due to right and left ventricular depolarization. Depolarisation of ventricle of hea occurs simultaneously bundle of His and Purkinje fibres.Ref: General pathology in Textbook of pathology HARSH MOHAN 6th Editon 