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 preceeds: \nSelect and explain. \nA. Ventricular ejection, B. Ventricular relaxation, C. Atrial contraction, D. Atrial relaxation', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ventricular ejection', 'role': 'assistant'}]