The correct answer is option 3: Cerebrum. The cerebrum is the largest part of our brain and is responsible for various higher functions, including thinking, reasoning, memory, and voluntary movements. It is divided into two hemispheres, the left and the right, which are connected by a bundle of nerve fibers called the corpus callosum. The outer layer of the cerebrum is known as the cerebral cortex, which is highly folded to increase its surface area. This folding allows for a greater number of neurons and connections, which are critical for processing information. The cerebrum also contains various lobes, such as the frontal lobe, parietal lobe, occipital lobe, and temporal lobe, each playing a unique role in different functions of the brain.