What facts can you compile that would support a theory that multicellular eukaryotes developed from unicellular prokaryotes?

Multicellular eukaryotes evolved from unicellular prokaryotes by the process of endosymbiosis

Explanation:

All living beings have evolved from three groups of animals closely related with each other. Domains: Archaea, bacteria and eukarya. the archaea and bacteria are unicellular organism surrounded by single cell water and and coiled stand of DNA. Eukaryotic cells are more complex and with a linear strand of DNA which is in the nucleus. Actually mitochondria which had evolved from a free living bacterium which was swallowed by another cell. The host cell benefited from the chemical energy that mitochondria produced and mitochondria in turn is benefited to be inside the protected environment. Mitochondria is the main organelle which the multicellular eukaryotes with unicellular prokaryotes.