What is a primary function of the nervous system?

A primary function of the nervous system is to control both voluntary and involuntary body activities. This system is responsible for transmitting signals throughout the body, enabling communication between different parts, coordinating movements, and processing sensory information. For instance, it allows for conscious actions such as walking or speaking, which are voluntary activities, as well as unconscious processes like respiration and reflexes, which are involuntary. The nervous system's role in these areas is crucial for maintaining homeostasis and responding to external stimuli, making it essential for overall body function and survival.

In contrast, the other options pertain to different biological systems. Regulating metabolic functions is primarily the responsibility of the endocrine system, circulation of blood is managed by the circulatory system, and supporting the skeletal structure is the realm of the skeletal system itself. Each of these systems has distinct functions that, while interrelated, do not overlap with the primary role of the nervous system.