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: Medicine
[{'content': 'CSF glucose level is - \nSelect and explain. \nA. Half the plasma glucose, B. 2/3 of plasma glucose, C. 1/3 of plasma glucose, D. Same as plasma glucose', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]