I would say the tone of this sentence is formal.
        
                    
             
        
        
        
The etymology of the word impose includes:
> in (Latin) meaning in or upon + ponere (Latin) meaning put = imponere (Latin) meaning inflict or deceive or poser (Old French) meaning "to put". Therefore, the answer is option D. To put.
        
                    
             
        
        
        
<span>William Faulkner's speech at the Nobel Banquet at the City Hall in Stockholm, December 10, 1950 * ... Because of this, the young man or woman writing today has forgotten the ... It is easy enough to saythat man is immortal simply because he will endure: that ... The poet's, the writer's, duty is to write about these things.</span><span>
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A, as this is where the story turns from bad to good.
Or D, as this is where the story turns from good to bad. 
Most likely, the answer is A.