Which statement correctly distinguishes the central and peripheral nervous systems?

• A. Central nervous system includes brain and spinal cord; peripheral nervous system includes all nerves outside CNS
• B. Central nervous system includes nerves outside the brain; peripheral includes brain
• C. Central nervous system includes skin receptors; peripheral includes muscles
• D. Central nervous system includes only the brain

Answer: (A)

The main idea is how the nervous system is organized into a central control hub and the network that connects it to the body. The central nervous system consists of the brain and spinal cord, where information is processed and coordinated. The peripheral nervous system includes all nerves outside the CNS—the pathways that carry sensory signals to the brain and spinal cord and motor commands from them, along with autonomic nerves that regulate organs. So the statement that correctly distinguishes them is that the CNS includes the brain and spinal cord, while the PNS includes all nerves outside the CNS. The other options mix up what belongs to each part: nerves outside the brain are part of the PNS, not the CNS; the brain is part of the CNS, not the PNS; skin receptors are located in the PNS; and the CNS is not limited to the brain alone because the spinal cord is also part of it.