Final answer:
All the options listed (Diencephalon, Cerebellum, Brainstem, Spinal Cord) are parts of the central nervous system, which comprises the brain and spinal cord, therefore the correct answer is E. None of the above.
Step-by-step explanation:
The question asks which of the listed options is NOT part of the central nervous system (CNS). The central nervous system is composed of two major components: the brain and the spinal cord. Within the brain, there are several regions including the cerebrum, the diencephalon, the brain stem, and the cerebellum.
Choices A (Diencephalon), B (Cerebellum), and C (Brainstem) are all parts of the brain. Choice D (Spinal Cord) is the other major component of the CNS. Since all the listed options are parts of the CNS, the correct answer is E. None of the above.