A foil provides contrast with the main character.<span>
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Themselves
This reflexive pronoun is the best fit because it needs to agree with the antecedent--in this case "scholars". Because scholars is plural, the pronoun also needs to be plural. Themselves is a plural reflexive pronoun, so it will properly complete the sentence. 
        
             
        
        
        
Answer:
B. It introduces a new central idea to focus on.
Explanation:
I say this but I didn't read the passage, so excuse me if I'm wrong. It doesn't seem to be A, sense it isn't contrasting a statement. It really could be C as well, but this seems to be something it would focus on. It could not be D because it is not a concluding sentence, it would leave the passage in an awkward state. This is why I say B.
 
        
                    
             
        
        
        
Answer:
B
He didn't like the science teacher because he smelled like a pine tree.