The correct answer is B. The author's primary purpose in writing "The Strangers That Came to Town" was to show readers how unjust, cruel, and incorrect prejudices can be. After the main conflict is resolved, the narrator goes on to prove how incorrect everyone's prejudices about the Duvitches were.
The story, written by Ambrose Flack, tells the story of the Duvitch, Croatian emigrants who come to a small American town, where because of prejudice suffer discrimination despite not deserving it for being kind and friendly people.