What are process of endosymbiosis is supported by the discovery that chloroplasts have their own?

The process of endosymbiOSis is supported by the discovery that chloroplasts have their own DNA, which is circular and resembles the DNA of prokaryotes, particularly cyanobacteria. Additionally, chloroplasts replicate independently of the cell's nucleus through a process similar to binary fission. They also possess double membranes, consistent with the idea that they originated from an engulfed prokaryotic ancestor. This evidence suggests that chloroplasts were once free-living organisms that formed symbiotic relationships with early eukaryotic cells.