This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'The most important function of the microcirculation is: \nSelect and explain. \nA. The exchange of nutrients and wastes between blood and tissue, B. The filtration of water through capillaries, C. The regulation of vascular resistance, D. The autoregulation of blood flow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. The exchange of nutrients and wastes between blood and tissueEach of the choices is a function of the microcirculation, but its most important function by far is to provide tissue with nutrients and remove the wastes.', 'role': 'assistant'}]