This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
[{'content': 'Glucose in CSF \nSelect and explain. \nA. 1/3 of blood glucose, B. 1/2 of blood glucose, C. 2/3 of blood glucose, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Glucose level in CSF: 64mg/dL Plasma: 100mg/dL CSF/Plasma ratio turns out to be: 0.64 Which is closer to 2/3=0.66 Ref:Ganongs Review of medical physiology;23 rd edition ; pg : 571 ; table 34-2.', 'role': 'assistant'}]