This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'Isovolumetric relaxation ends immediately after \nSelect and explain. \nA. AV Valve doses, B. When ventricular pressure falls below aortic pressure, C. When ventricular pressure falls below atrial pressure, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]