Question:
Why does the virus need a host in order to multiply?
Answer:
Use the cells' resources
Explanation:
A virus is typically a is a DNA or RNA moiety encased in a protein capsule. The capsule is usually specific to the class and type of virus and it lends to the virulence of the entity. In order for infection to be established the virus must bypass the host's immune system and it's immune response and invade a host cell. There it will incorporate it's genetic material into the hosts' nucleus and harness the machinery that it does not in itself possess in order to make multiple copies of itself. It uses the host cell's DNA replication machinery, proteins amino acids and energy among other things before it bursts out of the cell and destroys it. This continues for some time and eventually the host may perish. The virus will then be passed along to a different host where it's replication using that hosts machinery will continue. 
 
        
             
        
        
        
<span>By 1990, the former communist leaders were out of power, free elections were held, and Germany was whole again.</span>
        
             
        
        
        
The Iron Curtain forms the Western border of the Soviet Satellite nations: all the countries to the West, also called the "West Bloc" were capitalist and the countries on the East are called "East Bloc". 
So the relationship was: the Iron Curtain was to the West of the Soviet Satelite nations.  
        
             
        
        
        
Your correct answer would be D.