Thermococcus, Methanococcus and Methano-bacterium exemplify

(1) bacteria  whose DNA is relaxed or positively supercoiled but which have a cytoskeleton as well as mitochondria

(2) bacteria that contain a cytoskeleton and ribosomes

(3) archaebacteria that contains protein homologous to eukaryotic core histones

(4) archaebacteria that lack any histones resembling those found in eukaryotes but whose DNA is negatively supercoiled