The endosymbiotic theory provides an explanation of the origin of chloroplasts which traits of chloroplasts supports this explanation

Chloroplast do not reproduce

chloroplasts rely on proteins that are made by the cell

chloroplasts are larger than prokaryotic cells

chloroplasts have their own DNA

The answer is chloroplasts have their own DNA

The endosymbiotic theory explains that mitochondria and chloroplasts descended from the same type of bacteria. According to the endosymbiotic theory, a host cell ingested symbiotic bacteria, which specialized into chloroplasts. The evidence for this theory is that mitochondria and chloroplasts have their own circular DNA and transcriptional and translational machinery.