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

Fact 2: Nitrogen deficiency increases the stress on the plants.

Given the two facts above, answer the question "What does bacteria in the soil help to prevent?" with the following options: 
- contamination
 - colder weather
 - Pollution
 - anemia
 - plant stress
 - Greenhouse gasses
 - toxins
 - disease


 

     plant stress    