Consider the following statements regarding free-living nitrogen-fixing microorganisms: 1. Azotobacter is a free-living, aerobic nitrogen-fixing bacterium found in neutral to alkaline soils. 2. Beijerinckia is a free-living, anaerobic nitrogen-fixing bacterium prevalent in acidic soils. 3. Rhodospirillum is a free-living, anaerobic, photosynthetic nitrogen-fixing bacterium. Which of the statements given above are correct?

Options:

• A: 1 and 2 only
• B: 2 and 3 only
• C: 1 and 3 only
• D: 1, 2 and 3

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