Answer:
<h2><u>
A. Having a nucleus</u></h2>
Explanation:
Many organisms have nuclei, but certain types of one-celled prokaryotes and bacteria do not have one. 
 
        
                    
             
        
        
        
Environmental scientists are using GPS ( It is effective but expensive) aerial monitoring (Quick but not the easiest), RFID tags, (mostly for long-term monitoring) and hidden cameras are used to study polar bear behavior without interruption to their environment.
        
             
        
        
        
I’m pretty sure the answers are- Oxygen and glucose
        
             
        
        
        
I believe the answer is an egg
        
                    
             
        
        
        
It's A. Volcanic Island Arcs