I believe it’s C because the heart pumps blood through the body
        
                    
             
        
        
        
Answer:
The correct answer is d. hydronium ion.
Explanation:
Hydronium ion is a positively charged molecule that has three hydrogen atom bonded with an oxygen atom. Hydronium ion is formed when the water molecule gains an extra H+ ion from somewhere.  
This H+ ion easily form bonds with one of the lone pairs present on the water molecules. H2O is also a polar molecule and has a partially positive charge due to which the extra H+ ions get attracted to the negative pole of water and make hydronium ion. Therefore the correct answer is d.
 
        
             
        
        
        
Mark on the address to send the new address please please let me know what
        
             
        
        
        
Answer:
carbon dioxide is released during leaf respiration (intake of oxygen), but it is quickly reabsorbed during photosynthesis.
Explanation: