Match the following.
\[ \begin{array}{|c|l|c|l|} \hline & \textbf{List-I} & & \textbf{List-II} \\ \hline A & \textit{Azotobacter} & I & \text{Anaerobic Nitrogen Fixer} \\ B & \textit{Clostridium} & II & \text{Symbiotic Nitrogen Fixer} \\ C & \textit{Rhizobium} & III & \text{Free-living Aerobic Fixer} \\ D & \text{Leghemoglobin} & IV & \text{Oxygen Buffering Protein} \\ \hline \end{array} \]
The correct answer is