This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'QRS complex is due to? \nSelect and explain. \nA. Ventricular repolarization, B. Ventricular depolarization, C. Atrial repolarization, D. Atrial depolarization', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 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)', 'role': 'assistant'}]