Q: You are presented with the quiz "what doesn't riding a bike cause?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "riding a bike does not cause pollution" and "carbon monoxide is, of course, an air pollutant". So, what's the best answer to the question?

OPTIONS: (A). Allergies (B). harmful substances (C). Decrease bodily water (D). Greenhouse gasses (E). carbon monoxide (F). global warming (G). Dehydration (H). chemical changes
The answer is:
(E).