Question

9. Veins allow blood to flow in one
direction only due to the presence of
O
force
O
thick walls
O valves
septum​

Answer 1

B. Thick Walls

Capillaries connect the arteries to veins. ... They're similar to arteries but not as strong or as thick. Unlike arteries, veins contain valves that ensure blood flows in only one direction. (Arteries don't require valves because pressure from the heart is so strong that blood is only able to flow in one direction.)