A Pathologist Claims It's Much Easier to Determine the Causative

A pathologist claims it's much easier to determine the causative agent of meningitis than that of an infection of the skin or intestines. Is this true? Why or why not?

A) It's not true. An infection is an infection, and it's always difficult to track down the exact causative agent. The organ system involved in the illness has nothing to do with identification of the causative agent.
B) It's true. The CNS is generally microbe free, whereas the skin and intestines have a diverse normal microbiota. Separating out a pathogenic causative agent from the normal microbiota in these areas would be much harder to do than in the CNS.
C) It's not true. The ventricles of the brain can provide a direct route for microbes to enter the CNS from the bloodstream. Therefore, it would be just as likely to find a pathogenic microbe in the CNS as it would be in the skin or intestines.
D) It's true. There are only 1 or 2 microbes that can cause meningitis, yet there are hundreds (if not thousands) that can cause skin/intestinal infections. This makes it much easier to determine the causative agent for a case of meningitis.
E) It is not true. It is almost impossible to obtain a sample of cerebrospinal fluid, which is required to diagnose meningitis. It is far simpler to obtain a sample from the skin or intestines, so it is easier to diagnose diseases of these systems.