Answer:
D
Explanation:
Methanogens are prokaryotes and therefore have prokaryotic cells. They are single-celled archaea. They are found in hypoxic conditions like the first stomach of ruminants where they digest molecules like cellulose and produce methane as a byproduct. The rest are composed of eukaryotic cells which are much larger than prokaryotic cells and their organelles are membrane-bound (unlike prokaryotes).
