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
[{'content': 'Depolarisation of atria on ECG is seen as \nSelect and explain. \nA. P-wave, B. QRS complex, C. T-wave, D. ST segment', 'role': 'user'}, {'content': 'Answer: A \nExplanation: P wave shows atrial depolarizationQRS complex shows ventricular depolarization T wave shows ventricular repolarizationST segment represents the duration from the end of ventricular depolarization to the beginning of ventricular repolarizationRef: Textbook of medical physiology by N Geetha,2nd edition, page no. 136', 'role': 'assistant'}]