Riding a bike does not cause pollution.
Carbon monoxide is, of course, an air pollutant.
Riding a bike does not cause carbon monoxide.
what doesn't riding a bike cause?
[A] Allergies
[B] harmful substances
[C] Decrease bodily water
[D] Greenhouse gasses
[E] carbon monoxide
[F] global warming
[G] Dehydration
[H] chemical changes