Final answer:
Cerebrospinal fluid occupies the subarachnoid space, central canal, and ventricular system; the correct answer to where CSF is not found is D. subdural space.
Step-by-step explanation:
Cerebrospinal fluid (CSF) is found in various locations within the central nervous system (CNS), including the subarachnoid space, the central canal, and the ventricular system, which comprises the lateral ventricles, third ventricle, and fourth ventricle. It serves as a cushion and provides mechanical and immunological protection to the brain and spinal cord. The CSF is produced by a specialized membrane called the choroid plexus, located in all four ventricles. It flows through the ventricular system, enters the subarachnoid space through median and lateral apertures, and is then reabsorbed into the blood at the arachnoid granulations.
In contrast, the subdural space, which lies between the dura mater and the arachnoid mater, does not contain CSF. Hence, the correct answer to the question "Cerebrospinal fluid is found in all of the following except the" is D. subdural space.