This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2017, Subject name: Medicine
[{'content': 'The PR interval in ECG denotes? \nSelect and explain. \nA. Atrial depolarization only, B. Atrial depolarization with A - V conduction, C. Ventricular depolarization and ventricular repolarization, D. Atrial depolarization with atrial repolarization', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Atrial depolarization only - P- Wave Ventricular depolarization and ventricular repolarization - QT interval', 'role': 'assistant'}]