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
Depolarisation of atria on ECG is seen as 
Select and explain. 
A. P-wave, B. QRS complex, C. T-wave, D. ST segment
A: P-wave
Answer: A: P-wave 
Explanation: 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