This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Cerebral blood flow is regulated by all except \nSelect and explain. \nA. Blood pressure, B. Aerial PC02, C. Potassium ions, D. Cerebral metabolic rate', 'role': 'user'}, {'content': "Answer: C \nExplanation: Intracranial pressureMean aerial pressure at brain levelThe direct dilator action of CO2 is most pronounced in the skin and brainIf the cerebral blood flow is known, it is possible to calculate the consumption or production by the brain of O2, CO2, glucose- in other words, cerebral blood flow is regulated with the above factors which depend on the cerebral blood flowRef: Ganong's Review of Medical Physiology Twenty-Third Edition Page No:575", 'role': 'assistant'}]