Cyanobacteria, also known as blue-green algae, possess two defining biological characteristics that match this option:

Oxygenic: They perform oxygenic photosynthesis, meaning they use water as an electron donor and release oxygen as a byproduct, similar to green plants.

With Nitrogenase: Many cyanobacteria possess the enzyme nitrogenase, which allows them to fix atmospheric nitrogen into usable forms like ammonia. Because nitrogenase is sensitive to oxygen, these bacteria often use specialized thick-walled cells called heterocysts to create an anaerobic environment for the enzyme to function.

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