Organ system is the answer according to me if it is one word question
        
                    
             
        
        
        
An exothermic chemical reaction is  change in the chemicals that can never be undone, an exothermic solution is a combination of chemicals 
        
             
        
        
        
Explanation:
Introduction. The tendency to maintain a stable, relatively constant internal environment is called homeostasis. The body maintains homeostasis for many factors in addition to temperature. For instance, the concentration of various ions in your blood must be kept steady, along with pH and the concentration of glucose.
I THINK THIS IS THE ANSWER GOOD LUCK 
 
        
             
        
        
        
Answer:
I think is B because at stage 4 we can observe that different kinds of cell formed(the cell on the edge is different from the inner cell)
Explanation: