Final answer:
The cerebrum is divided into two hemispheres by the longitudinal fissure. This significant anatomical feature runs from the front to the back of the brain and is distinct from other brain features such as the corpus callosum, central sulcus, and postcentral gyrus.
Step-by-step explanation:
The cerebrum is divided into two hemispheres by a deep groove known as the longitudinal fissure. This major landmark in brain anatomy separates the left hemisphere from the right hemisphere, and is often depicted in brain diagrams as the prominent split found at the top of the brain, running from the front to the back. The corpus callosum lies beneath the cerebral cortex within the cerebrum, acting as the primary communication pathway that connects the two hemispheres, whereas the longitudinal fissure is the observable furrow that actually divides the two halves of the cerebrum. Other sulci and gyri on the brain's surface, such as the central sulcus and the postcentral gyrus, serve as landmarks to delineate the different lobes of the brain but do not divide the hemispheres. The correct answer to the question is option 4, the longitudinal fissure.