Biofertilizers include

Options

A. Rhizobium, Azotobacter, Azospirilium and blue green algae (BGA).
B. Glomus, Anabaena, Nostoc, Frankia.
C. Rhodospirullum, Rhodopseudomonas, Clostridium, Bacillus, Beijerinkia.
D. All of these

Answer

### Step-by-Step Solution:

1. **Definition of Biofertilizers**: Biofertilizers are substances that contain living microorganisms which promote plant growth by increasing the supply or availability of primary nutrients to the host plant.

2. **Types of Biofertilizers**: Common types of biofertilizers include:
- **Nitrogen-fixing bacteria**: These bacteria convert atmospheric nitrogen into a form that plants can use. Examples include:
- **Rhizobium**: Forms symbiotic relationships with legumes.
- **Azotobacter**: A free-living nitrogen-fixing bacterium.
- **Azospirillum**: Associates with the roots of various plants.
- **Blue-green algae (Cyanobacteria)**: These organisms can perform photosynthesis and fix nitrogen, contributing to soil fertility.

3. **Other Microorganisms**: Additional microorganisms that can be considered biofertilizers include:
- **Glomus**: A genus of arbuscular mycorrhizal fungi that enhance nutrient uptake.
- **Anabaena** and **Nostoc**: These are also nitrogen-fixing cyanobacteria.
- **Francia**: Another nitrogen-fixing organism associated with certain plants.

4. **Other Beneficial Bacteria**: Other bacteria that contribute to soil fertility include:
- **Rhodospirillum**
- **Rhodopseudomonas**
- **Clostridium**
- **Bacillus**
- **Bajorchinia**

5. **Conclusion**: All of these microorganisms help in increasing the nutrient content and fertility of the soil, making them effective biofertilizers. Therefore, the correct answer to the question "Biofertilizers include" is "all of these."