Which of the following correctly summarizes why bacteria and archaea are not in the same kingdom? . a. only archaea have cell membranes made from straight chains of peptidoglycan.. b. only bacteria are both prokaryotic and single-celled organisms.. c. archaea are believed to be the ancestor of bacteria and therefore cannot be in the same kingdom as bacteria.. d. their cell walls are created from different substances and bbacteria has an rna polymerase that archaea lacks.. i think its d!