B. Mitochondria
The process of cellular respiration is essentially when oxygen and carbon transfuse themselves together to create carb on dioxide, which in turns creates energy. 
The entire process is formed in the powerhouse of the cell, or in other words, the mitochondria. 
A part of this question that may have been confusing is the answer, "lungs". Since respiration is correlated to the lungs, you may have been confused. However, this is a process that occurs within your cells, so on a small scale than your entire body. 
 
        
             
        
        
        
The body will stop making proteins that need it
        
                    
             
        
        
        
Answer:
I believe a layer deep underground would have older things, because the ground could erode over time causing the fossil to sink into the ground.
 
        
             
        
        
        
Answer:
The circulatory system to provide this oxygen and to remove the waste products of metabolism.The exchange of gases between the blood and tissue cells is internal respiration.
Explanation:
the circulatory and respiratory systems work together to circulate blood and oxygen throughout the body. Air moves in and out of the lungs through the trachea, bronchi, and bronchioles
hope this helps