used as a nutrient by plants fixed by bacteria in the soil converted into oxygen absorbed into the atmosphere by lightning
I gave my students this multiple choice question: After nitrogen becomes part of the lithosphere, what is the next change that nitrogen will undergo?

Only one answer is correct among these 4 choices:
- used as a nutrient by plants
- fixed by bacteria in the soil
- converted into oxygen
- absorbed into the atmosphere by lightning

Could you tell me which one is correct?

fixed by bacteria in the soil