Answer:
The answer is D. Cyanobacterium.
Explanation:
A Eubacteria are microscopic organisms that have prokaryotic cells. Cyanobacteria, also known as blue-green algae, are eubacteria that are known to have been living on our planet for more than 3 billion years. Cyanobacteria are a phylum of the Bacteria domain that comprises bacteria capable of performing oxygenic photosynthesis. They are the only prokaryotes that carry out this type of photosynthesis,