Question

which best describes nitrogen fixation?○ nitrogen fixation is the process of creating free nitrogen for plants to absorb.○ nitrogen fixation is the breakdown of nitrogen in the soil.○ nitrogen fixation is the conversion of nitrogen gas into a usable form.○ nitrogen fixation is the destruction of the bonds between nitrogen and other elements.

Explanation:

Nitrogen fixation refers to the biological or industrial process that converts atmospheric nitrogen gas ($N_2$), which is unavailable to most organisms, into a chemically reactive form (like ammonia, $NH_3$) that can be used by plants and other living things. The other options are incorrect: it does not create free nitrogen for absorption, break down soil nitrogen, or destroy bonds between nitrogen and other elements.

Answer:

Nitrogen fixation is the conversion of nitrogen gas into a usable form.