This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiac Cycle, Subject name: Physiology
[{'content': "'Y' descent in the JVP is due to: \nSelect and explain. \nA. Atrial diastole, B. Closure of the tricuspid valve, C. Opening of the tricuspid valve, D. Isovolumetric relaxation of right ventricle", 'role': 'user'}, {'content': 'Answer: C \nExplanation: "y" wave indicates fall of right atrial pressure due to opening of tricuspid valve leading to ventricular filing.', 'role': 'assistant'}]