Select the odd one w.r.t. biofertilisers

Options

A. Bacteria
B. Fungi
C. Cyanobacteria
D. Viruses

Answer

To solve the question of selecting the odd one with respect to biofertilizers, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Biofertilizers**:
- Biofertilizers are live organisms that enhance the nutrient quality of the soil. They are used to improve soil fertility and promote plant growth.

2. **Identifying the Options**:
- The options provided are:
1. Bacteria
2. Fungi
3. Cyanobacteria
4. Viruses

3. **Analyzing Each Option**:
- **Bacteria**: Certain bacteria, such as Rhizobium, are known to fix nitrogen in leguminous plants and are classified as biofertilizers.
- **Fungi**: Some fungi, like mycorrhizal fungi, also contribute to soil fertility and can act as biofertilizers by enhancing nutrient uptake in plants.
- **Cyanobacteria**: These are photosynthetic bacteria that can fix atmospheric nitrogen and are utilized as biofertilizers, especially in rice paddies.
- **Viruses**: Unlike the other three, viruses are acellular entities and do not contribute to soil fertility or plant growth in the same way. They are not classified as biofertilizers.

4. **Conclusion**:
- Based on the analysis, the odd one out with respect to biofertilizers is **Viruses**. They do not function as biofertilizers, while bacteria, fungi, and cyanobacteria do.

### Final Answer:
The odd one with respect to biofertilizers is **Viruses**.

---