The right answer is D.Chloroplasts have their own DNA.
The endosymbiotic theory, or the hypothesis of endosymbiosis, is the hypothesis that the chloroplasts and mitochondria of eukaryotic cells arise from the incorporation (endocytosis) by some archaea of bacteria with which they have maintained an endosymbiotic relationship.
The resemblance between a current eukaryotic cell chloroplast and a photosynthetic bacterium (Cyanobacterium) is supported by several characters:
* the chloroplast DNA is circular and not associated with histones as in bacteria,
this DNA codes for a part of the chloroplastic proteins (semi-autonomous organelles),
part of the synthesis of chloroplast proteins is carried out in the chloroplast, thanks to the presence of ribosomes which have analogies with bacterial ribosomes,
* any plastid comes from a pre-existing plastid. When cells do not have a plastid (some white cells of variegated leaves), the daughter cells do not have a plastid,
* the division of chloroplasts follows a rhythm independent of the division of the nucleus,
* In higher plants, the two membranes of the chloroplast envelope are different: the inner membrane and thylakoid membranes have similarities (lipid composition) with the bacterial membranes.
All these observations today represent strong arguments of the endosymbiotic theory. Endosymbiosis could occur at different times and in different ways, by absorption by a primitive cell (Prokaryote or Eukaryote) from another cell (Prokaryote or Eukaryote). This is called primary or secondary endosymbiosis.
