Final answer:
The key term that refers to the major division between the right and left hemispheres of the brain is the longitudinal fissure.
Step-by-step explanation:
The key term that refers to the major division between the right and left hemispheres of the brain is the longitudinal fissure, which is the deep groove that separates the brain into two halves. Another option presented in the question, the corpus callosum, is a thick bundle of axons that connects the left and right hemispheres, allowing for communication between them. However, the primary division is marked by the longitudinal fissure.