Which of the choices below are sources of pollution that is the most difficult to track and regulate? a. lawn fertilizer runoff b. a waste treatment plant c. a factory d. a nuclear power plant

I think the correct answer from the choices listed above is option A. Lawn fertilizer is the source that is the most difficult to track and regulate. This is because fertilizer used in a lawn are not measured strictly and most likely there are no clear regulations about the use of it. Also, runoff of such is very difficult to follow. It can go anywhere. Hope this answers the question.