Willa Cather does not suggest in the story that his aunt's life in Nebraska is positive even though he has positive memories of her. This makes B and C wrong. A does not work either because in the story, the speaker does not talk about any intellectual or mental demands. He does, however, list the various physical tasks his aunt had to perform such as taking care of livestock, cooking for many hands, staying up late ironing, etc. D is correct.
