Which two structures make up the central nervous system (CNS)?

The central nervous system (CNS) is composed of the brain and the spinal cord. The brain serves as the control center for processing information, coordinating sensory data, and initiating responses. It is responsible for higher cognitive functions, emotions, and learning. The spinal cord acts as a critical pathway for transmitting signals between the brain and the rest of the body. It carries motor commands from the brain to various body parts and relays sensory information from the body back to the brain. This unique combination of the brain and spinal cord allows the CNS to function effectively in controlling and integrating bodily functions, thereby playing a crucial role in overall nervous system operation.

In contrast, options involving pairs such as "brain and nerves" or "spinal cord and peripheral nerves" include components that are part of the peripheral nervous system instead. The peripheral nerves connect the CNS to limbs and organs, facilitating communication but do not constitute the CNS itself. The term "brainstem" refers to a part of the brain rather than a distinct structure, as it is included in the broader category of the brain. Thus, the accurate representation of the CNS consists solely of the brain and spinal cord, making the answer that identifies these two structures correct.