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). 
 
        
             
        
        
        
Answer:
Nitrogen cycle works through various stages like, nitrogen fixation, nitrification, assimilation, ammonification, denitrification etc. It is a building block for protein and DNA
Explanation:
Nitrogen is an element abundantly found in the atmosphere, also its building block for proteins as well as nucleic acid i.e. DNA formation. In nitrogen cycle , the nitrogen is being prepared from inert nitrogen.  The nitrogen cycle has several processes like nitrogen fixation, in this the inert nitrogen is being converted to organic nitrogen with the help of certain micro-organism.
 Nitrification, plants cannot absorb directly nitrogen so bacteria help the plants to convert the nitrogen into ammonia form in this stage. Assimilation, another stage in which plants starts absorbing various forms of nitrogen from the soil.i.e. nitrate, nitrite and ammonium. Ammonification, here plants and animals have nitrogen in there body after death various microbes help in decomposition in this stage. Denitrification, in this stage the return back of nitrogen takes place.
 
        
             
        
        
        
Valley-Glacier
Landslide-gravity
Frost wedging-ice
Canyon-river
I think this is correct, sorry if I’m wrong :)