Final answer:
Cerebrospinal fluid is mainly reabsorbed into the venous circulation via arachnoid granulations that protrude into the superior sagittal sinus, eventually draining into the jugular veins.
Step-by-step explanation:
The correct answer to the question is b) Arachnoid granulations. The cerebrospinal fluid (CSF) is reabsorbed into the venous circulation via the arachnoid granulations. These are outpocketings of the arachnoid membrane that protrude into the dural sinuses, specifically into the superior sagittal sinus, where the bulk of CSF reabsorption occurs. The reabsorbed CSF then travels through the venous system to be returned to circulation. Venous return involves blood passing through the CNS, draining into a series of dural sinuses, such as the superior sagittal sinus, and eventually draining into the jugular veins, carrying the reabsorbed CSF with it.