Fact 1: Soil is formed by rocks eroding.

Fact 2: Examples of such rock include sandstone and shale .

Given the two facts above, answer the question "What forms soil?" with the following options: 
- Earthworms
 - single-celled organisms
 - an external framework
 - space travel
 - most organisms
 - sandstone eroding
 - water freezing
 - ice forming


 

      sandstone eroding   