In which type of vessels does gas exchange between blood and tissues occur to the greatest extent-veins?

The given statement is incorrect. Gas exchange between blood and tissues occurs to the greatest extent in capillaries, not veins. Capillaries are the smallest blood vessels with thin walls that allow for the exchange of oxygen, carbon dioxide, and other nutrients between the blood and surrounding tissues. Veins are larger blood vessels that carry deoxygenated blood back to the heart.