Select the mismatch :

Options

A. Frankia-Alnus
B. Rhodospirillum-Mycorrhiza
C. Anabaena-Nitrogen fixer
D. Rhizobium-Alfalfa

Answer

To solve the question of selecting the mismatch, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Analyze the first pair: Francia and Alnus**
- Francia is a nitrogen-fixing bacterium that forms a symbiotic relationship with the genus Alnus (alders). This pairing is correct as Francia helps in nitrogen fixation in the roots of Alnus trees.

2. **Analyze the second pair: Rhodospalum and Mycorrhiza**
- Rhodospalum is not typically associated with mycorrhizal relationships. Mycorrhizae are generally fungi that form symbiotic relationships with plant roots, while Rhodospalum (if referring to Rhodospirillum) is a type of purple bacteria. This pairing seems incorrect.

3. **Analyze the third pair: Anabaena and Nitrogen Fixer**
- Anabaena is indeed a genus of nitrogen-fixing cyanobacteria. This pairing is correct as Anabaena is well-known for its ability to fix atmospheric nitrogen.

4. **Analyze the fourth pair: Rhizobium and Alfalfa**
- Rhizobium is a genus of bacteria that forms symbiotic relationships with legumes, including alfalfa, to fix nitrogen. This pairing is also correct.

### Conclusion:
The mismatch is found in the second pair: **Rhodospalum and Mycorrhiza**.

### Final Answer:
The mismatch is **Rhodospalum and Mycorrhiza**.

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