Answer:
They weren't treated like humans, but more as a commodity, something that can be used and abused without care. In the North, people were against slavery and working to end it, so naturally, you'd go somewhere safer, where you're actually seen as a human being with feelings and unalienable rights. 
 
        
             
        
        
        
No main purpose was fur trading 
        
                    
             
        
        
        
Seems the answer would be D.