Based on the endosymbiotic theory, what cell would result from the endosymbiosis of a cell with a cyanobacterium?

The answer is a eukaryotic cell.
According to endosymbiotic theory, the result from the endosymbiosis of a cell with a cyanbacterium is a eukaryotic cell that can produce its own food. Eukaryote refers to the organisms whose cells have a nucleus and other organelles are enclosed within membranes.