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': 'Shape of the arterial pulse is influenced by \nSelect and explain. \nA. Viscosity of blood, B. Velocity of blood, C. Arterial wall expansion, D. Cross sectional area of artery', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Arterial pulse is caused by the ventricular systole that leaves a pressure wave along the arterial wall during each contraction.', 'role': 'assistant'}]