Common sources of dust are carpet, paper, hair, and skin. Some dust comes from fossil fuels. Each time a car or bus spews out exhaust, it adds to the amount of dust in the air. Other dust comes from pollen. When a volcano erupts or when there is a wildfire, the resulting ash becomes dust. Glaciers also produce dust. Water flowing from beneath glaciers is often milky instead of clear because it is dusty. Some scientists believe that dust can fertilize the oceans. In the past, scientists have added iron dust to the sea, believing that the dust would help plant life.

A. Abundant
B. Stationary
C Mysterious
D Investigated