The cross-sectional area of the aorta is $3 \mathrm{cm}^{2},$ and the average
velocity of blood leaving the heart into the aorta is 30 $\mathrm{cm} / \mathrm{s}$ . If
the combined effective cross sectional area of the body's capillaries is $600 \mathrm{cm}^{2},$ what is the average flow rate in a capillary?
$$\begin{array}{l}{\text { A. } 1 \mathrm{cm} / \mathrm{s}} \\ {\mathrm{B} .2 \mathrm{cm} / \mathrm{s}} \\ {\mathrm{C} \cdot 0.01 \mathrm{cm} / \mathrm{s}} \\ {\mathrm{D}, 0.15 \mathrm{cm} / \mathrm{s}} \\ {\mathrm{E} .0 .2 \mathrm{cm} / \mathrm{s}}\end{array}$$