What, according to mukherjee in "a four-hundred-year-old woman," is her "duty" as a writer? answer is a i belive aka to educate the american public about third world countries.

The answer is C. to encourage a reinterpretation of what constitutes being an American

The reason why I know it is C is because I used and everyone said it was A and I got it wrong when I put that, then I read the story and C makes so much more sense.

sentence lenght varies according to word choice.you select which word to use and that will require to use other expressions that collocate with the word chosen.sentence length will vary   according to the choice of words you make to express your ideas.  

i don't get it. is this a question on a test? i need more information to solve.