The source of the water in lakes, reservoirs, and ponds may be rivers, streams, groundwater, rainfall, melting snow runoff, or a combination of these. Any of these sources may carry contaminants. Because water exits from these water bodies at a slow rate, pollutants can become trapped and build up.
D) In DNA, adenine, thymine, guanine, and cytosine join together and carry all of the genetic information. RNA is made from adenine, uracil, cytosine, and guanine and is used to make proteins.
