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.

B) Overuse of fertilizer increases nitrogen levels in water runoff which can reach lakes.

Explanation:

Organic fertilizers can be detrimental to the environment, when abused. Problems that can stem from overusing fertilizers include runoff and erosion, the contamination of water supplies, and disruptions to aquatic life. ... Nitrates, phosphates, and other nutrients are abundant in common agricultural fertilizers.

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."