During biological nitrogen fixation, nitrogen is converted to

Options

A. ammonia
B. nitrate
C. nitrite
D. amino acid

Answer

### Step-by-Step Solution:

1. **Understanding Biological Nitrogen Fixation**:
- Biological nitrogen fixation is a process where atmospheric nitrogen (N₂) is converted into a more usable form by certain bacteria, primarily in the root nodules of leguminous plants.

2. **Identifying the Product of Nitrogen Fixation**:
- During this process, nitrogen is primarily converted into ammonia (NH₃). This is the key product of biological nitrogen fixation.

3. **Formation of Ammonium Ion**:
- The ammonia produced can then exist in an ionic form as ammonium ion (NH₄⁺) when it interacts with water in the soil.

4. **Subsequent Processes**:
- After ammonia is formed, it can undergo further transformations:
- **Ammonification**: The process where organic nitrogen is converted into ammonium.
- **Nitrification**: The conversion of ammonium into nitrites (NO₂⁻) and then into nitrates (NO₃⁻).
- **Denitrification**: The process where nitrates are converted back into nitrogen gas (N₂), completing the nitrogen cycle.

5. **Conclusion**:
- The question specifically asks about the product of biological nitrogen fixation. Therefore, the correct answer is that nitrogen is converted into ammonia during this process.

### Final Answer:
- **Ammonia (NH₃)**

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