Is there a passage to read???
        
             
        
        
        
D by presenting jazz as the Jacksonville of music
        
             
        
        
        
Hello there! 
The roots of the word barbarian came from ancient Greece. The word barbarian was generally used at that time to describe any non-Greeks. Therefore the answer would be D. Greek.
 
        
                    
             
        
        
        
<u>It helps the writers visualize the inside of a black hole. </u>
<em>The other options can described bluntly and scientifically with just names and numbers. </em>
If the writer were to use more formal writing to describe things so abstract like a black hole, it would be hard for the common reader to understand. 
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for example, 
The black hole looks like a giant vacuum of nothingness (informal) 
The black hole is like a mass whose Schwarzchild radius is outside of itself (formal) 
Which is easier to understand? Most likely the first one because of the use of informal language and writing. 
Hope I helped!