9. Three percent of the world’s water resources are found as a. fresh water. c. icecaps and glaciers. b. salt water. d. groundwater. 10. Most of the pollutants in the ocean come from a. commercial boats and personal watercraft. b. spills from oil tankers. c. activities on land. d. leaking underground storage facilities. 11. The largest watershed in the United States is the a. Mississippi River. c. Colorado River. b. Yukon River. d. Rio Grande. 12. During the water treatment process, what is the purpose of adding chlorine to water? a. to remove large debris b. to form flocs c. to kill or limit bacterial growth d. to remove unwanted gases