Which part of the nervous system controls an individual's involuntary actions?

The autonomic nervous system plays a crucial role in regulating involuntary actions in the body, such as heartbeat, digestion, and respiratory rate. This system operates without conscious control, allowing the body to function smoothly in everyday activities. It’s divided into two main branches: the sympathetic and parasympathetic nervous systems. The sympathetic nervous system is involved in the "fight or flight" response, while the parasympathetic system promotes "rest and digest" functions.

In contrast, the central nervous system, which comprises the brain and spinal cord, is primarily responsible for processing and integrating information. The peripheral nervous system encompasses all nerves outside the central nervous system and includes both voluntary and involuntary pathways, but it does not specifically control involuntary actions. Given that autonomic functions are regulated by the autonomic nervous system, it is the correct answer in this context.