The nitrogen fixing bacteria present in the root nodules of leguminous plant is

The correct answer is C. Rhizobium.

Rhizobium is a genus of bacteria that form a symbiotic relationship with legumes. These bacteria live in root nodules of legumes and fix atmospheric nitrogen into ammonia, which the plant can use to grow.

Salmonella is a genus of bacteria that can cause food poisoning. Clostridium is a genus of bacteria that can cause botulism. Pseudomonas is a genus of bacteria that can cause a variety of infections.

Rhizobium is the only genus of bacteria that forms a symbiotic relationship with legumes. The other three genera of bacteria can cause disease in humans or animals.