This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2018, Subject name: Physiology
[{'content': 'Cardiac event at the end of isometric relaxation phase: \nSelect and explain. \nA. Atrioventricular valves open, B. Atrioventricular valves closes, C. Corresponds to peak of C wave in JVP, D. Corresponds to T wave in ECG', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Isometric relaxation - Semilunar valves have closed. - AV valves yet to open In isometric relaxation ventricular muscle continues to relax without change in ventricular volume | Intraventricular pressure decreases back to the diastolic levels | AV valves open JVP correlation to cardiac cycle A wave: Atrial contraction C wave: Beginning of ventricular contraction bulging of AV valves back towards atria V wave: Towards end of ventricular contraction X wave: Ventricular contraction Y wave: Atrial emptying tricuspid valve opens', 'role': 'assistant'}]