Fact 1: Riding a bike does not cause pollution.

Fact 2: Air pollution can cause diseases and harm crops.

Given the two facts above, answer the question "What form of transportation does not cause diseases or harm crops?  " with the following options: 
- Earthworms
 - animals
 - automobile
 - mechanical
 - train
 - airplane
 - Movement
 - bicycle


 

        bicycle 