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 Nitrogen levels in soil correspond to nitrogen levels in the sediment at the bottom of a lake.
C. Too little nitrogen in soil causes algae to move into aquatic environments like lakes.
D. Overuse of fertilizer increases nitrogen levels in water runoff which can reach lakes.