The answer B.Since,Diffusion is driven by differences in concentration. When chemical substances such as perfume are let loose in a room, their particles mix with the particles of air. ... Diffusion in gases is quick because the particles in a gas move quickly. It happens even faster in hot gases because the particles of gas move faster.
The motto means that you should reduce the trash that is causing pollution. Also, that you should follow the idea of conservation and conserve any renewable resources by recycling them.