Which of the following organisms is incapable of performing nitrogen fixation?

Nitrogen fixation is a process that converts atmospheric nitrogen into a form that can be used by plants and other organisms. This process is carried out by certain types of microorganisms, including cyanobacteria, Azotobacter, and Rhizobia. Fungi, however, are not capable of fixing nitrogen. Unlike other nitrogen-fixing organisms, fungi lack the enzymes necessary to convert atmospheric nitrogen into a usable form for themselves or other organisms.