Final answer:
The correct answer is D. Brain stem, cerebellum, cerebrum, and diencephalons, as these parts make up the three major divisions of the brain along with important inner structures.
Step-by-step explanation:
The brain is divided into three major parts, each with different functions: the brain stem, the cerebellum, and the cerebrum. The cerebrum is the largest part of the brain and is further divided into left and right hemispheres, with each hemisphere consisting of four lobes: frontal, parietal, temporal, and occipital. The brain stem, through its part known as the medulla, connects to the spinal cord, while the cerebellum is located at the base of the brain and is involved in controlling balance and coordinating movement. Additionally, inner structures of the brain such as the hypothalamus and thalamus play essential roles in controlling the endocrine system and various involuntary functions.
Therefore, the correct answer to the question is D. Brain stem, cerebellum, cerebrum, and diencephalons, as the diencephalons include the thalamus and hypothalamus which are crucial inner parts of the brain.