The total volume of CSF is: (A) 50 ml, (B) 100 ml, (C) 150 ml, (D) 275 ml
Answer is C. In humans, the volume of CSF is about 150 mL and the rate of CSF production is about 550 mL/d. Thus the CSF turns over about 3.7 times a day.(Ref: Ganong's Review of Medical Physiology Twenty-Third Edition)