The corpus callosum connects:

• A. Connects hemispheres
• B. Relays sensory information
• C. Regulates sleep cycles
• D. Connects brain to spinal cord

Answer: (A)

The main idea is how the brain wires itself to share information between its two halves. The corpus callosum is the largest bundle of nerve fibers that links the left and right cerebral hemispheres, acting as a communication highway. This interhemispheric bridge lets sensory, motor, and cognitive information travel from one side of the brain to the other so that activities requiring both sides can be coordinated smoothly.

That’s why it’s the best answer: its primary role is connecting hemispheres and enabling integrated processing across the two sides of the brain. It isn’t the main relay for sensory information—that job involves other structures like the thalamus—nor is it responsible for regulating sleep cycles, which are controlled by areas such as the hypothalamus and brainstem, nor does it connect the brain to the spinal cord—the brain-to-spinal pathway is established by other motor tracts emerging from the brainstem and cortex.