Which of the following is a free living bacteria that can fix nitrogen in the soil?
Spirulina, Azospirillum, Sonalika

Explanation

To solve the question "Which of the following is a free-living bacteria that can fix nitrogen in the soil?" we need to analyze the options provided: Spirulina, Azospirillum, and Sonalika.

### Step-by-Step Solution:

1. **Identify the Options**:
- The options given are Spirulina, Azospirillum, and Sonalika.

2. **Analyze Spirulina**:
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