This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Misc., Subject name: Physiology
Normal CSF volume in adults is 
Select and explain. 
A. 50 ml, B. 150 ml, C. 500 ml, D. 300 ml
B: 150 ml
Answer: B: 150 ml 
Explanation: (B) 150 ml # CEREBROSPINAL FLUID:> Lumbar CSF pressure is normally 70-180 mm CSF.> Up to pressures well above this range, the rate of CSF formation is independent of intraventricular pressure.> However, absorption, which takes place largely by bulk flow, is proportionate to the pressure.> At a pressure of 112 mm CSF, which is the average normal CSF pressure, filtration and absorption are equal.> Below a pressure of approximately 68 mm CSF, absorption stops.