Select the mismatch:

Options

1. A$\begin{cases}Frankia & - & \text{A}\text{l}\text{n}\text{u}\text{s}\end{cases}$
2. B$\begin{cases}Rhodospirillum & - & \text{M}\text{y}\text{c}\text{o}\text{r}\text{r}\text{h}\text{i}\text{z}\text{a}\end{cases}$
3. C$\begin{cases}Anabaena & - & \text{N}\text{i}\text{t}\text{r}\text{o}\text{g}\text{e}\text{n}\text{f}\text{i}\text{x}\text{e}\text{r}\end{cases}$
4. D$\begin{cases}Rhizobium & - & \text{A}\text{l}\text{f}\text{a}\text{l}\text{f}\text{a}\end{cases}$