Fact 1: Bacteria in soil convert atmospheric nitrogen into a form usable by plants.

Fact 2: Spores are a dormant form of bacteria.

Given the two facts above, answer the question "What can change atmospheric nitrogen into a form used by plants?" with the following options: 
- Conifers
 - mutations
 - Collagen
 - earthworm
 - sugar
 - Enzymes
 - spores
 - wind


 

       spores  