An organization that works to protect the environment notices that a large number of lake organisms are killed when a sudden algae bloom depletes the lake of oxygen. Why do they decide to test the nitrogen level in the soil of near-by farms?
A) Using too little fertilizer causes crops to leach nitrogen from lakes.
B) Overuse of fertilizer increases nitrogen levels in water runoff which can reach lakes.
C) Nitrogen levels in soil correspond to nitrogen levels in the sediment at the bottom of a lake.
D) Too little nitrogen in soil causes algae to move into aquatic environments like lakes.