They are all eukaryotic, I hope this was the answer you were looking for :D
 
        
             
        
        
        
D is the answer 
It’s cell,tissue,organ, organ system
        
             
        
        
        
Researchers and doctors hope stem cell studies can help to increase understanding of how diseases occur, and to better understand how diseases and conditions develop.
        
             
        
        
        
C no because many species went extinct without leaving fossils behind