Question

what is the purpose of heart valves?
to filter waste products from the blood
to control blood flow
to regulate blood pressure
to produce red blood cells
to transport oxygen in the blood

Explanation:

Heart valves open and close to ensure blood flows in one direction (e.g., from atria to ventricles, and from ventricles to arteries). This prevents backflow. For example, the mitral valve ensures blood flows from the left atrium to the left ventricle and not the other way.

Answer:

To control blood flow