Which of the following sources of pollution would be the most difficult to track and regulate? a. lawn fertilizer runoff b. a waste treatment plant c. a factory d. a nuclear power plant

a. lawn fertilizer runoff

Pollution as a result of lawn fertilizer runoff would be difficult to track and regulate due to the possible breadth of the area affected. Toxins can be spread throughout the land area as well as be carried downstream if near a water source. Sewer systems, rivers, lakes, ponds, etc. can all be negatively affected by lawn fertilizer runoff. Irrigation or rain water can carry toxins for many miles before the effects are detected. Tracing the source of the toxins would be difficult, especially in a highly populated area.