Blood may flow in the aorta with a speed of 30 cm/s and in the capillaries with a speed of only 0.1 m/s. Why is there such a large difference in speed? A. the capillaries are much further from the heart than the aorta. B. the very narrow capillaries present a large resistance to blood flow com- pared to the large diameter aorta. C. the total cross-sectional area of the lumens of the capillaries is much greater than the cross-sectional area of the aorta. D. the length of the aorta is short compared to the length of a capillary.
Option C. The total cross-sectional area of the lumens of the capillaries is much greater than the cross-sectional area of the aorta.
