What system regulates the activity of internal organs and includes the sympathetic and parasympathetic systems?

The autonomic nervous system is responsible for regulating the activities of internal organs, such as the heart, lungs, and digestive system, without conscious control. It operates automatically to maintain homeostasis in the body.

Within the autonomic nervous system, there are two main components: the sympathetic and parasympathetic systems. The sympathetic system prepares the body for 'fight or flight' responses, increasing heart rate and energy availability, while the parasympathetic system promotes 'rest and digest' activities, slowing down heart rate and supporting bodily maintenance functions.

The central nervous system, which consists of the brain and spinal cord, primarily processes information and coordinates responses, while the somatic nervous system manages voluntary movements by controlling skeletal muscles. The peripheral nervous system encompasses all nerves outside the central nervous system but divides into the autonomic and somatic systems. Therefore, designating the autonomic nervous system as the correct answer highlights its specific role in regulating involuntary internal organ function through its sympathetic and parasympathetic pathways.