$Thermococcus$,$Methanococcus$,and $Methanobacterium$ are examples of:

• A
  Bacteria whose $DNA$ is relaxed or positively supercoiled but have a cytoskeleton and mitochondria.
• B
  Bacteria that contain a cytoskeleton and ribosomes.
• C
  Archaebacteria that contain protein homologous to eukaryotic core histones.
• D
  Archaebacteria that lack histones resembling those found in eukaryotes but whose $DNA$ is negatively supercoiled.