D, they need to be able to absorb and keep water to prevent drying out
        
                    
             
        
        
        
Answer:
The cardio-respiratory system works together to get oxygen to the working muscles and remove carbon dioxide from the body. During exercise the muscles need more oxygen in order to contract and they produce more carbon dioxide as a waste product.
Explanation:
 
        
             
        
        
        
The function o the phytoplankton in ocean ecosystem is A. producer. <span>Phytoplankton produce their own energy through a biological process or chemical reaction. They are a key factor of the aquatic biome.</span>
        
                    
             
        
        
        
Carbon dioxide is used to build sugars. I think it's the only one