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': 'Which vessel regulates blood flow? \nSelect and explain. \nA. Aery, B. Aerioles, C. Venules, D. Capillaries', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. b' aerioleDistribution of blood flow is mainly regulated by aeriole, by alteration in their diameter.Increase or decrease the pephenl resistance to blood flow.", 'role': 'assistant'}]