Your heart's mitral valve does an awfully big job. Letting blood from the left atrium of the heart into the left ventricle without
losing a drop is one of the toughest tasks in the circulatory system. In fact, if the system was suddenly opened at that point, the
force of the valve closing would send blood five feet in the air.
In this passage, the author's purpose is to
A describe the circulatory system.
B convince readers of the stress on the mitral valve.
C inform readers of defects in the mitral valve.
D minimize the importance of the mitral valve.