Final answer:
Eukaryotes are different from archaea and bacteria because they have a nucleus and mitochondria, making a) and c) correct, hence the answer is d) a and c are correct.
Step-by-step explanation:
Eukaryotes differ from archaea and bacteria in that eukaryotic cells contain a nucleus and other membrane-bound organelles such as mitochondria, which are not found in archaean prokaryotic cells or bacterial prokaryotic cells. While eukaryotic cells have a nucleus that houses their DNA, prokaryotes like bacteria and archaea have a nucleoid region where their DNA resides without a nuclear membrane. Additionally, bacterial cell walls contain peptidoglycan, whereas archaea do not, and neither archaea nor bacteria have mitochondria. Therefore, the correct answers are a) they contain a nucleus and c) they contain mitochondria, making d) a and c are correct the accurate choice.