What is the function of veins in the circulatory system?

The function of veins in the circulatory system is to return blood toward the heart. Veins play a crucial role in completing the circulatory loop by carrying deoxygenated blood from the body's tissues back to the heart, where it can be pumped to the lungs for reoxygenation. This process is essential for maintaining a steady flow of blood, which is vital for delivering nutrients and removing waste products from cells.

In contrast, the other options detail functions that do not align with the primary role of veins. For example, blood is transported from arterioles to capillaries by arterioles themselves, which are small blood vessels that regulate blood flow into capillary beds. Carrying blood to the lungs is a function predominantly associated with the pulmonary arteries, which transport deoxygenated blood from the heart to the lungs. Moreover, conducting oxygen-rich blood is primarily the function of arteries, which carry oxygenated blood away from the heart to the rest of the body. Thus, the primary role of veins is indeed to return blood toward the heart, making this choice the correct representation of vein function in the circulatory system.