Which of the following represents a function of the respiratory system?

The option that accurately represents a function of the respiratory system is taking in oxygen and expelling carbon dioxide. The respiratory system is primarily responsible for gas exchange, which is vital for maintaining the body's homeostasis. This process occurs in the lungs, where oxygen from the air is transferred into the bloodstream while carbon dioxide, a waste product of metabolism, is removed from the blood and expelled from the body during exhalation.

Oxygen is essential for cellular respiration, a process that provides energy to cells, and the expulsion of carbon dioxide helps to maintain the acid-base balance in the body. This fundamental function is critical for sustaining life, as the body relies on a continuous supply of oxygen for various physiological processes.

The other options relate to functions of other body systems. For instance, pumping blood is a primary function of the circulatory system, regulating body temperature involves various systems including the integumentary and endocrine systems, and hormone production is a function of the endocrine system. Thus, while all these processes are critical to overall health and function, they do not pertain to the respiratory system’s primary role.