Fact 1: Being exposed to wind can cause erosion of soil.

Fact 2: Wind erosion is slowed by wind barriers such as trees and shrubs.

Given the two facts above, answer the question "what blocks erosion?" with the following options: 
- roots
 - Raft
 - bamboo
 - trees
 - bushes
 - Roads
 - rivers
 - streams


 

    trees     