The Velocity of Blood Flow Is the Lowest in Capillaries

The velocity of blood flow is the lowest in capillaries because ________.

A) the capillaries have internal valves that slow the flow of blood
B) the diastolic blood pressure is too low to deliver blood to the capillaries at a high flow rate
C) the systemic capillaries are supplied by the left ventricle, which has a lower cardiac output than the right ventricle
D) the total cross-sectional area of the capillaries is greater than the total cross-sectional area of the arteries or any other part of the circulatory system