In people who stand for long periods, blood tends to pool in the lower limbs and this may result in varicose veins. What causes the varicose veins?
A. an aneurysm or weak point in an artery
B. an aneurysm or weak point in an vein
C. failure of the venous valves
D. failure of the lymphatic valves
E. a ruptured aneurysm in a vein