Which system is composed of the brain and spinal cord?

The correct answer identifies the Central Nervous System (CNS) as the system composed of the brain and spinal cord. The CNS is the primary control center for the body, responsible for processing and transmitting information. It integrates sensory data and coordinates bodily functions and responses. The brain acts as the command center, processing information and making decisions, while the spinal cord serves as the main pathway for transmitting signals between the brain and the rest of the body.

In contrast, the Peripheral Nervous System (PNS) includes all the nerves that branch out from the CNS and extend to the limbs and organs, functioning primarily to connect the CNS to the rest of the body. The Autonomic Nervous System is a subdivision of the PNS that regulates involuntary bodily functions like heart rate and digestion, while the Somatic Nervous System involves voluntary control over skeletal muscles and sensory information. Each of these systems plays a distinct role in overall nervous system function, but the brain and spinal cord's central roles are what classify them as components of the CNS.