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': 'CSF sugar is - \nSelect and explain. \nA. Half of blood sugar, B. 1/3 of blood sugar, C. 2/3 of blood sugar, D. Same as blood sugar', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans is'c' i.e.,2/3 of blood sugarCSF / plasma glucose ratio is 0.64.", 'role': 'assistant'}]