What does the central nervous system (CNS) consist of?

The central nervous system (CNS) is comprised of the brain and spinal cord. This system is essential for processing information and coordinating activity throughout the body. The brain serves as the control center, responsible for interpreting sensory information, making decisions, and directing responses. The spinal cord acts as a vital conduit for transmitting signals between the brain and the rest of the body, facilitating reflexes and motor control.

The other options do not accurately describe the CNS. While the peripheral nerves and limbs are part of the peripheral nervous system (PNS) and play important roles in transmitting signals to and from the CNS, they are not considered part of the CNS itself. The brain only option omits the spinal cord, which is a critical component of the CNS. Similarly, stating spinal nerves only neglects the brain's crucial functions in the central nervous system's operations. Understanding the distinction between the CNS and the PNS is fundamental in recognizing how the body's nervous systems work together to facilitate reactions and responses.