I believe your answer for this problem is C
Literature and the Holocaust have a complicated relationship. This isn't to say, of course, that the pairing isn't a fruitful one—the Holocaust has influenced, if not defined, nearly every Jewish writer since, from Saul Bellow to Jonathan Safran Foer, and many non-Jews besides, like W.G. Sebald and Jorge Semprun. Still, literature qua art—innately concerned with representation and appropriation—seemingly stands opposed to the immutability of the Holocaust and our oversized obligations to its memory. Good literature makes artistic demands, flexes and contorts narratives, resists limpid morality, compromises reality's details. Regarding the Holocaust, this seems unconscionable, even blasphemous. The horrors of Auschwitz and Buchenwald need no artistic amplification.
Answer: to reveal the challenges of social activism
This is the most accurate answer. In this excerpt, the author does not describe a routine action. The event was an anomaly in the lives of African Americans. The author also does not talk about the actions of police forces, as the father gave in without the intervention of the police. Finally, the author does not actually describe the pride the author feels for her father. What the excerpt shows is the challenges of social activism, and the judgement that activists faced when trying to do the right thing.
The choice of this phrase has a paradoxical meaning in a way that Bartleby refuses to do the task asked from him and the expression of this rejection. It is a refusal, but at the same time it is a polite refusal because even when his boss asks again "You will not?", he answers again with "I prefer not". The phrase emphasizes Bartleby's passive resistance. The different use of the phrase, of course could have had a different effect in the story. It might cause a different demonstration and a different ending for the story. The boss could have replied differently because the refusal would be not polite then. However, the choice is intentional because of the development of the story. Therefore, it is suitable in its own way.