What organisms, other than bacteria, are able to perform nitrogen fixation? a. viruses c. algae b. trees d. protists

I think the correct answer would be algae. The organism that can perform nitrogen fixation from the choices would be algae. Nitrogen fixation is a process where nitrogen in the atmosphere is converted to ammonia by nitrogen-fixing bacteria which includes cyanobacteria or the blue green algae. 

The answer is c. 320 g