The role of a watershed is to
a. purify water.
b. act as a drainage area.
c. collect fish from rivers and streams.
d. protect wetland areas.

The right answer is B. act as a drainage area.

A watershed or watershed is the space drained by a watercourse and its tributaries. All the waters that fall into this space converge towards the same exit point called an outlet: stream, lake, sea, ocean, etc.

The watershed is bounded by a watershed that often corresponds to the ridge lines but not always. Generally a watershed develops beyond the ridge lines. A watershed is a divergent line of slopes. Rainwater on both sides of this line flows in two different directions, carrying with them dissolved or suspended elements such as sediments and pollution.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.