Answer:
It means that from time to time, organisms change in form and function 
Explanation:
As organisms live, they change and develop/mutate into better, stronger, and more functional creatures. This is in addition, because of the cells in the body.
 
        
             
        
        
        
<h2><u>its is (A) skeletal and muscular</u>  </h2><h2>because without skeletal ur body want be able to move also the muscular system do the sam but it give u strength to move  it.</h2>
        
                    
             
        
        
        
Parietal and frontal.. whichever one your looking for 
        
             
        
        
        
Answer:
Population trend refers to changes over time and can include changes in ranging behavior (e.g., distance and route) and distribution, biogeography (e.g., size of population) and life-history (e.g., birth and death rates).