anything humans add to the atmosphere and oceans any substance that is harmful to the environment any substance that is a waste product of industry a substance that does not break down over time
I gave my students this multiple choice question: Which of these best defines the term "pollutant"?

Only one answer is correct among these 4 choices:
- anything humans add to the atmosphere and oceans
- any substance that is harmful to the environment
- any substance that is a waste product of industry
- a substance that does not break down over time

Could you tell me which one is correct?

any substance that is harmful to the environment