Question

which living organism processes nitrogen in the atmosphere and makes it available to other living forms in a usable form? a. bacteria b. plants c. humans d. animals

Explanation:

Nitrogen fixation is the process of converting atmospheric nitrogen ($N_2$) into a usable form (like ammonia) for other organisms. Bacteria (specifically nitrogen - fixing bacteria, e.g., Rhizobium in root nodules of legumes or free - living bacteria like Azotobacter) perform this process. Plants absorb fixed nitrogen, humans and animals obtain nitrogen from consuming other organisms, and they don't fix atmospheric nitrogen. So bacteria are the organisms that process atmospheric nitrogen to make it available to other living forms.

Answer:

A. bacteria