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': 'Time taken for electrical conduct from SA node to AV node in ECG is \nSelect and explain. \nA. PR interval, B. ST segment, C. QT interval, D. Cannot be determined by ECG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: PR interval is the interval between beginning of p wave to the beginning of QRS. It indicates atrial depolarization and AV nodal delay. (REF: GANONG&;S REVIEW OF MEDICAL PHYSIOLOGY)', 'role': 'assistant'}]