Answer:
a. the blood pressure decreases. the bblood in the A that is the artery is higher as the artery carries the oxygenated blood which is directly pumped out of the heart.so the artery's pressure is higher where as the capillaries pressure decreases when compared with artery. the blood in the capillary flows slowly and smoothly as capillary needs time to exchange the substance between the body cells and the blood. the vein carry the deoxygenated blood back to the heart so their pressure is low.
b.the highest pressure is found in the artery because it carries the oxygenated blood and the heart pump the blood with great force thus tge artery have the highest pressure . and it also wanted to transport the oxygen quickly to other parts of the body.
c. valves. these prevent the backflow of the blood in capillary as the blood moves against the gravity.so valves prevent the blood from going back . therefore the valves help the blood in veins to move back to heart. (not sure)
