Which of the following best supports the claim that organisms of different domains share a common ancestor?
(A) Photosynthesis occurs in chloroplasts, and the citric acid cycle occurs in mitochondria.
(B) Glycolysis occurs in both prokaryotic cells and eukaryotic cells.
(C) Introns are present in eukaryotic DNA but not in prokaryotic DNA.
(D) Errors in DNA synthesis provide some of the genetic variation in a population.