What is the primary function of the cardiorespiratory system?

The primary function of the cardiorespiratory system is to carry oxygen in the blood through the heart and blood vessels. This system is critical for sustaining life as it provides oxygen to the body's tissues, which is necessary for cellular respiration and energy production. The heart pumps oxygenated blood from the lungs to the rest of the body, while returning deoxygenated blood back to the lungs for reoxygenation. This process not only supports the delivery of essential nutrients to cells but also assists in the removal of carbon dioxide and other waste products.

The other options, while relevant to overall bodily functions, do not encapsulate the primary role of the cardiorespiratory system. For instance, filtering toxins from the blood involves the kidneys more than the cardiorespiratory system. Regulating body temperature is a function primarily handled by the integumentary system (skin) and the hypothalamus, and though the cardiorespiratory system can influence temperature through blood flow, it is not its primary role. Meanwhile, producing carbon dioxide is a byproduct of metabolic processes occurring in the cells, but the cardiorespiratory system's main duty is the transportation of oxygen, not the production of carbon dioxide for exhalation.