Evidence for the bacterial origin of chloroplasts is supported by observations that both chloroplasts and bacteria A - VCE - SSCE Biology - Question 12 - 2017 - Paper 1

Chloroplasts are believed to have originated from free-living bacteria through the process of endosymbiosis. One key piece of evidence supporting this theory is that both chloroplasts and certain bacteria possess a single circular chromosome, akin to prokaryotic DNA structure. This contrasts with the linear DNA found in the nuclei of eukaryotic cells. The presence of a circular chromosome in chloroplasts suggests that they share a common ancestry with bacteria, reinforcing the idea of their evolution from a symbiotic relationship with ancestral bacteria. Therefore, option C is the correct choice.