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: Medicine
[{'content': 'The ‘v’ wave of venous waveform represents \nSelect and explain. \nA. Ventricular systole, B. Ventricular diastole, C. Atrial systole, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The v wave represents atrial filling (atrial diastole) and occurs during ventricular systole. The height of the v wave is determined by right atrial compliance as well as the volume of blood returning to the right atrium either antegrade from the cavae or retrograde through an incompetent tricuspid valve.', 'role': 'assistant'}]