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': 'Of the following which one correlates with isovolumetric contraction phase \nSelect and explain. \nA. AV opening and aortic and pulmonary valve closure, B. AV closure and aortic and pulmonary valve opening, C. Both valves are closed, D. Both valves are open', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]