What do arteries primarily do in the circulatory system?

Arteries primarily carry oxygenated blood away from the heart to the rest of the body, which is why the answer is correct. Their primary function is to transport this oxygen-rich blood to various tissues and organs, where it is needed for cellular respiration and energy production.

Arteries have thick, elastic walls that allow them to withstand and regulate the high pressure at which blood is pumped by the heart. This elasticity also enables them to accommodate varying amounts of blood as needed by the body's requirements during different activities.

Other choices refer to functions that are characteristic of different components of the circulatory system. For example, deoxygenated blood is primarily carried by veins back to the heart, gas and nutrient exchange occurs in the capillaries, and while arteries play a role in blood pressure regulation, it is primarily through their structure and elasticity that they accommodate the pressure rather than "regulating" in a responsive way like other mechanisms in the cardiovascular system.