The primitive prokaryotes responsible for the production of biogas from the dung of ruminant animals, include the Halophiles, Thermoacidophiles, Methanogens, and Eubacteria.

The correct option is C. Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals.