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': 'Distribution of blood flow in mainly regulated by the: \nSelect and explain. \nA. Aeries., B. Aerioles., C. Capillaries., D. Venules', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Aerioles', 'role': 'assistant'}]