Because some of them are immune and only works for one thing in the system
 
        
             
        
        
        
D. i belive hope this helps u buddy if not then im sorry....
-Lawrence $.
 
        
                    
             
        
        
        
Answer:
They serve us as shelters. 
It protects us from many natural hazards like, rain,heat etc. 
It provides a privacy to every person. 
 
        
                    
             
        
        
        
Answer:
The correct option is : d. Syncytia
Explanation:
Syncytia are the multinucleated cells formed from multiple fusions of the uninuclear cells.
During a infection, an infected cell fuse together with the neighboring host cells, leading to the formation of large multinucleated cells, called syncytia.
Viruses like herpesviruses, induce the formation of multinucleated syncytia cells.