You are presented with the question "What allows soil to convert atmospheric nitrogen into a usable form by plants?" and the following answer choices: 
- hydrogen and oxygen
 - diseased soil
 - peachleaf willow
 - bacteria-free soil
 - healthier soil
 - nutrients
 - virus filled soil
 - Cooking

Now knowing that bacteria in soil convert atmospheric nitrogen into a form usable by plants and more bacteria mean healthier soil, choose the best answer.


 

     healthier soil    