Which body structure is primarily responsible for crossing sensory information to the opposite side of the brain?

The medulla is primarily responsible for crossing sensory information to the opposite side of the brain due to its role in processing signals from the body. Specifically, the medulla contains pathways known as the pyramidal decussation, where motor fibers cross from one side of the brainstem to the opposite side of the spinal cord.

This crossing is essential for integrating sensory information and coordinating motor control, allowing the brain to process signals from one side of the body and send out motor responses to the opposite side. As a result, sensory input from the right side of the body is processed in the left hemisphere of the brain, and vice versa.

Other structures listed, such as the cerebral cortex, spinal cord, and cerebellum, have different roles. The cerebral cortex is primarily involved in higher functions like perception, thought, and decision-making. The spinal cord mainly acts as a conduit for signals to and from the brain but is not responsible for the direct crossing of sensory information. The cerebellum plays a key role in coordination and balance but is not the primary site for crossing sensory information. Thus, the medulla's specific anatomical and functional characteristics make it the correct answer for this question.