What is free nitrogen?

A.) nitrogen that is ready for plants to use
B.) nitrogen that has been fixed by bacteria
C.) nitrogen that cannot be used by organisms
D.) nitrogen that is returned to the soil by decomposers
THE ANSWER IS C.)

Hello, The answer is C.

Explanation:

Because, They can use only the nitrogen that is already in compound form. Certain types of bacteria are able to use the free nitrogen in the air to make nitrogen compounds through a process called nitrogen fixation. Some bacteria are decomposers and break down the complex nitrogen compounds in dead organisms and animal wastes. Hope That Helps!