Azotobacter/Anabena is free living bacteria.

Explanation

### Step-by-Step Solution:

1. **Identify the Organisms**: The question mentions two organisms: Azotobacter and Anabena. We need to determine which of these is a free-living bacteria.

2. **Define Azotobacter**: Azotobacter is a type of bacteria that is known for its ability to fix nitrogen. It is classified as an aerobic bacterium, which means it requires oxygen for its growth and metabolic processes.

3. **Define Anabena**: Anabena is a genus of cyanobacteria, which are photosynthetic bacteria. Like Azotobacter, Anabena is also capable of fixing nitrogen from the atmosphere.

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