Nitrogen fixation, the process of making nitrogen usable for living things, happen most in

A) bacteria

B) Plants

C) The ocean

D) Consumers

The nitrogen gas must be changed to a form called nitrates, which plants can absorb through their roots. The process of changing nitrogen gas to nitrates is called nitrogen fixation. It is carried out by nitrogen-fixing bacteria. The bacteria live in soil and roots of legumes, such as peas.