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': 'Main site of peripheral vascular resistance is \nSelect and explain. \nA. Pre-Capillary arterioles, B. Pre-Capillary sphincters, C. Capillaries, D. Windkessel vessels', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Arterioles are the chief site of vascular resistance.', 'role': 'assistant'}]