Select the mismatch

Options

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

Explanation

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. **Option 1: Francia and Alnus**
- Francia is a gram-positive bacterium that forms a symbiotic relationship with Alnus (a type of alder tree). This relationship is known to be beneficial for both organisms.
- **Conclusion**: This option is correct.

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