Answer:
They bring dissolved nutrients to the surface of the ocean. They decrease the levels of oxygen at the surface of the ocean. They decrease the amount of nutrients at the surface of the ocean.
Explanation:
 
        
             
        
        
        
I think the correct answer from the choices listed above is option B. You can find methanogens in the human intestines. These organisms can  work with or without oxygen. Too much of oxygen for them is toxic. They are obligate anaerobes.
        
             
        
        
        
The combination of compression and high temperature causes the carbon bonds in the organic matter to break down. This molecular breakdown produces thermogenic methane natural gas.