This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head & Neck, Subject name: Anatomy
[{'content': 'The arachnoid villi allow cerebrospinal fluid to pass between which two of the following spaces? \nSelect and explain. \nA. Choroid plexus and subdural space, B. Subarachnoid space and superior sagittal sinus, C. Subdural space and cavernous sinus, D. Superior sagittal sinus and jugular vein', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The arachnoid villi are extensions of the arachnoid mater into the superior sagittal sinus. The villi allow for proper drainage of the CSF into the venous bloodstream from the subarachnoid space in which the CSF circulates. The villi are a crucial element in maintaining proper intracranial pressure and circulation of the CSF.', 'role': 'assistant'}]