I THINK its (A) im sorry if im wrong i tried reading about it 
 
        
                    
             
        
        
        
It is the abdominal cavity that contains the digestive organs.
        
             
        
        
        
Answer:
Explanation:
Most limestones actually start as calcium carbonate mud or shells precipitated by organisms in reefs or shallow shelf regions - the biosphere. Over time, the limestone is broken down into its chemical parts and may come back to the surface as volcanic CO2 (in the atmosphere).
  
        
                    
             
        
        
        
The mitochondria produces energy to the cell while the ribosomes produce protei. 
Explanation:
 
        
             
        
        
        
It is basically a structure which helps segregate the chormosomes in to the daughter cells
hope this was helpful