People with occupations that involve standing all day are at risk of varicose veins. Why should this be true? A. Veins have a larger lumen than arteries so hold more blood which distends them. B. Veins have only two tunics so their walls are more easily stretched into varicosity. C. Gravity acting on blood in the legs puts stress on the vessel walls increasing the likelihood that they will stretch and distort. D. When standing still, the valves stay open and blood accumulates in the leg veins.
Option C. Gravity acting on the blood withinside the legs of a standing person will increase the pressure at the walls of a vein. A weak point will result in the walls turning into distended and the valve now no longer running correctly.
