Which system encompasses the sympathetic and parasympathetic nervous systems?

The autonomic nervous system is the correct answer because it includes both the sympathetic and parasympathetic nervous systems, which are responsible for regulating involuntary bodily functions. The sympathetic nervous system prepares the body for 'fight or flight' responses during stressful situations, activating processes that increase heart rate, blood pressure, and energy availability. Conversely, the parasympathetic nervous system promotes 'rest and digest' activities, helping to conserve energy and facilitate bodily functions such as digestion and relaxation.

The central nervous system, which consists of the brain and spinal cord, is responsible for processing sensory information and coordinating the body's responses but does not include these two systems. The peripheral nervous system encompasses all nerves outside the central nervous system and includes both the autonomic and somatic nervous systems. The somatic nervous system specifically controls voluntary movements of skeletal muscles and does not encompass autonomic functions. Thus, the autonomic nervous system is the appropriate term for the system that includes both branches involved in regulating involuntary bodily functions.