Which process describes nitrogen fixation? a. animals eat plants containing nitrogen and return it to the soil through urination. b. bacteria take nitrogen from the air and convert it into a form usable by plants. c. organisms die and are decomposed into ammonia in the soil. d. plants take nitrogen from the air and store it in their roots.

B. Bacteria take nitrogen from the air and convert it into a form usable by plants.

Explanation:

Nitrate is a different form of nitrogen that is naturally found in different types of soil, water, or even the air. Plants use this nitrate to develop and grow, and used as plant proteins. Bacteria can take ammonia and turn it into nitrites, which is not usable by plants, and turn it into nitrates, which is usable to plants and will help them grow, as I stated above.