Riding a bike does not cause pollution, and pollution is anything that spoils the environment. Given these facts, what does not spoil the environment among the following options:
- Operating a factory
 - Driving a car
 - Riding a bike
 - food and shelter
 - hydrate their cells
 - lowered energy cost
 - Burning a fire
 - peachleaf willow


 

   Riding a bike      