The most accurate result from the endosymbiotic theory, which suggests that eukaryotes originated from prokaryotic cells engulfing other prokaryotic cells, would be:
similar structures in eukaryotes with slight variations depending on their use
This response reflects the idea that the endosymbiotic events led to the development of organelles (like mitochondria and chloroplasts) that have similar structures to certain prokaryotes, but with variations that suit the specific functions and needs of different eukaryotic organisms.