Final answer:
The division between the two brain hemispheres is known as the longitudinal fissure, not the corpus callosum which connects the two hemispheres for communication.
Step-by-step explanation:
The two hemispheres of the brain are separated by the longitudinal fissure. While the corpus callosum serves as the main connection between the two hemispheres, allowing for communication and the transfer of information, it is not the structure that divides them. The cerebral cortex refers to the outer layer of the brain, characterized by grooves and folds, and the longitudinal fissure is the most prominent groove that divides the brain into left and right hemispheres. Therefore, the correct answer to the question is B. longitudinal fissure.