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
[{'content': 'The daily production of CSF is \nSelect and explain. \nA. 550 ml, B. 1000 ml, C. 50 ml, D. 100 ml', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (A) 550 ml# Cerebrospinal fluid (CSF)> Total volume of CSF is 150 mis.> Daily production is 550 mls/day so the CSF turns over about 3 to 4 times per day.> CSF is formed by the choroid plexus (50%) and directly from the walls of the ventricles (50%).> CSF flows through the foramens of Magendie & Luschka into the subarachnoid space of the brain and spinal cord.> It is absorbed by the arachnoid villi (90%) and directly into cerebral venules (10%).> Normal intracerebral pressure (ICP) is 5 to 15 mmHg.> Rate of formation of CSF is constant and is not affected by ICR> Absorption of CSF increases linearly as pressure rises above about 7 cms H20 pressure.> At a pressure of about 11 cms H20, the rate of secretion & absorption are equal.', 'role': 'assistant'}]