Answer: The theme in Part A of the letter is the dilemma of migration faced by the African Americans after the Civil War. The sentence that best reveals this theme is D. Even though it seems as if more people are leaving each month, there are still divisions and arguments about leaving or staying.
This sentence shows that the narrator and her community are conflicted about whether to stay in Louisiana or move to Kansas, where they hope to find more opportunities and freedom. The sentence also implies that there is no clear or easy answer to this question, as there are pros and cons to both options. The sentence captures the essence of the theme by presenting the main problem and the different perspectives on it.