Fact 1: Riding a bike does not cause pollution.

Fact 2: Pollutants can be released either as gases or as particles.

Given the two facts above, answer the question "What does not release particles?" with the following options: 
- riding a bike
 - driving a car
 - influenza
 - monotremes
 - creating smog
 - burning coal
 - It remains dormant
 - peachleaf willow


 

 riding a bike        