a decrease in air temperature a decrease in water level fertilizer runoff from the farm exhaust gases from farm equipment
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: In a lake near a farm the growth of algae suddenly increased. This increase was most likely due to which of the following?
Possibilities:
- a decrease in air temperature
- a decrease in water level
- fertilizer runoff from the farm
- exhaust gases from farm equipment

fertilizer runoff from the farm