Use of Synthetic Fertilisers Often Leads to the Contamination of Groundwater

Multiple Choice

Use of synthetic fertilisers often leads to the contamination of groundwater with nitrates. Nitrate pollution is also a suspected cause of anoxic "dead zones" in the ocean. Which of the following might help reduce nitrate pollution?

A) growing improved crop plants that have nitrogen-fixing enzymes
B) adding nitrifying bacteria to the soil
C) adding denitrifying bacteria to the soil
D) using ammonia instead of nitrate as a fertiliser