The correct option is C Corpus callosum
The brain and the spinal cord are parts of the central nervous system. The brain is divided into forebrain, midbrain and the hindbrain.
The forebrain comprises of the cerebrum, thalamus and hypothalamus. The cerebrum is divided into right and left hemispheres. The corpus callosum allows communication between the right and the left cerebral hemispsheres. The outer layer of the cerebrum is called the cerebral cortex.
The brain stem comprises of parts of the hindbrain like pons and medulla and the midbrain.