Final answer:
The occipital lobe is not one of the three major subdivisions of the brain; it is a part of the cerebrum which includes several lobes responsible for different functions, with the occipital lobe being involved in vision.
Step-by-step explanation:
The question is asking to identify which option is not one of the three major subdivisions of the brain. The three major subdivisions of the brain are the cerebrum, cerebellum, and brainstem, as shown in the referenced figures. Among the given options, the occipital lobe is not one of these three major subdivisions; instead, it is a part of the cerebrum which is responsible for vision. The cerebrum itself is divided into several lobes, including the frontal, parietal, temporal, and occipital lobes.