- A Rhizobium
- B Nostoc
- C Azospirillum
- D Anabaena
Correct answer: C. Azospirillum
Explanation: Azospirillum is a free-living nitrogen-fixing bacterium found in the rhizosphere (root zone) of grasses and cereals, enhancing their nitrogen supply.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers