- A Symbiotically in root nodules
- B Freely in the soil
- C In partnership with legumes
- D Inside leaf cells
Correct answer: B. Freely in the soil
Explanation: Azotobacter is a free-living soil bacterium that fixes atmospheric nitrogen independently without forming symbiotic associations.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers