Which nervous system includes 31 pairs of spinal nerves and 12 pairs of cranial nerves?

The correct answer identifies the peripheral nervous system, which comprises all the nerves that lie outside the brain and spinal cord. This system includes 31 pairs of spinal nerves that emerge from the spinal cord, and 12 pairs of cranial nerves that originate from the brain. These nerves serve to connect the central nervous system (which includes the brain and spinal cord) to various parts of the body, facilitating communication between the central nervous system and limbs or organs.

The central nervous system itself does not encompass spinal or cranial nerves; instead, it comprises the brain and spinal cord. The autonomic nervous system is a subdivision of the peripheral nervous system responsible for regulating involuntary bodily functions, but it does not stand alone as a complete system including all peripheral nerves. Lastly, the sympathetic nervous system is another subdivision of the autonomic nervous system that specifically governs responses to stress or emergencies, but it’s not a comprehensive description of all cranial and spinal nerves. This is why the peripheral nervous system is the correct choice, as it accurately captures the entirety of the spinal and cranial nerve organization.