Where does most of the nitrogen in earths atmosphere come from?
a: fires
b: erosion
c: bacteria
d: the breakdown of carbon dioxide

Explanation:

This is the only answer that make sense, because nitrogen fixation is carried out by bacterias, algae and human activity. When organisms use it and release it, nitrogen is suffer a breakdown process, traveling as a gas to the atmosphere.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint