Their are lots of methods on being astute (:
 
        
                    
             
        
        
        
You didn't add the following?
        
             
        
        
        
Nick has a lunch with Gatsby and Wolfshiem is there.  He mentions to Nick that<span> he is a gentleman of
“good breeding,” not the type to go after anybody’s wife or anything</span>
        
             
        
        
        
Answer:
D seems the most convincing but i could be wrong.