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': 'At the end of the isometric relaxation phase \nSelect and explain. \nA. Atrioventricular valves open, B. Atrioventricular valves close, C. Corresponds to "C" wave in JVP, D. Corresponds to T wave in ECG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: At the end of Isovolumetric relaxation, the intraventricular pressures drop to less than the atrial pressure resulting in the opening of Atrioventricular valves Ref : Ganong 25th ed/page 539', 'role': 'assistant'}]