The author states that the water in a reservoir may contain harmful microbes. Which detail from the text best supports this?
A Animals may not be able to survive the changes to their habitat when rivers are dammed.
B Sunlight contains UV light that is invisible to people and can cause sunburns.
C The Environmental Protection Agency requires that drinking water be tested for contaminants.
D Groundwater happens when rain or other precipitation soaks deep into the soil.