Identify the option that has correct statements regarding biofertilizers.
a. Rhizobium and azotobacter are symbiotic microorganisms.
b. Azospirullum and blue-green algae are non - synbiotic microorganisms .
c. Mycorrhizae is the symbiotic phosphate solubilizing organism.
d. Actinomycetes is the non-symbiotic nitrogen-fixing microorganism.

Options

A. a and b are correct
B. a and d are correct
C. b and c are correct
D. b and d are correct

Answer

To solve the question regarding the correct statements about biofertilizers, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Evaluate Statement A**:
- **Statement**: Rhizobium and Azotobacter are symbiotic microorganisms.
- **Analysis**: Rhizobium is indeed a symbiotic nitrogen-fixing bacterium that forms a relationship with leguminous plants. However, Azotobacter is a free-living nitrogen-fixing bacterium and does not form a symbiotic relationship.
- **Conclusion**: This statement is **incorrect**.

2. **Evaluate Statement B**:
- **Statement**: Azospirillum and blue-green algae are non-symbiotic microorganisms.
- **Analysis**: Azospirillum is a free-living nitrogen-fixing bacterium, and blue-green algae (such as Anabaena and Nostoc) are also free-living and can fix nitrogen. Both are not symbiotic.
- **Conclusion**: This statement is **correct**.

3. **Evaluate Statement C**:
- **Statement**: Mycorrhizae is the symbiotic phosphate solubilizing organism.
- **Analysis**: Mycorrhizae are indeed a symbiotic association between fungi and the roots of higher plants. They help in the absorption of phosphorus and other nutrients from the soil.
- **Conclusion**: This statement is **correct**.

4. **Evaluate Statement D**:
- **Statement**: Actinomycetes is the non-symbiotic nitrogen-fixing microorganism.
- **Analysis**: Actinomycetes are a group of Gram-positive bacteria, and while some can fix nitrogen, they are generally not classified as non-symbiotic nitrogen-fixing microorganisms. They do not typically form symbiotic relationships like Rhizobium.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion:
The correct statements regarding biofertilizers are **B and C**. Thus, the answer is that options B and C are correct.