Fact 1: Soil is formed by weathering.

Fact 2: Rocks breakdown by weathering.

Given the two facts above, answer the question "What helps soil to form?" with the following options: 
- The planting of flowers
 - The breakdown of rocks
 - organic molecules
 - The changing of seasons
 - Organic compounds
 - swamp vegetation
 - evaporation
 - The movement of clouds


 

  The breakdown of rocks       