Final answer:
The only place where decussation doesn't happen is in the cerebrum.
Step-by-step explanation:
The correct answer is d) Cerebrum. Decussation refers to the crossing over of neural pathways from one side of the body to the other. In the brain, decussation occurs in various regions, such as the spinal cord, brainstem, and cerebellum. However, the cerebrum is the only region where decussation typically does not occur.