Which was the earliest multicellular organism that developed in the presence of oxygen?

A. cyanobacteria

B. prokaryotic

C. eukaryotic

D. algae

Presence of oxygen means that the organisms are not anaerobic so the answer is D. algae. Eukaryotic and prokaryotic cells can be anaerobic meaning that they live in circumstances where there's no oxygen. Algae were the first that required oxygen to thrive. Cyanobacteria are like other bacteria parts of the prokaryotic cell type.