The correct option is B Lin sorting through some books and sitting outside his house
The passage describes Lin's surroundings while we see Lin thumbing through a book. At the beginning, we also see Lin flipping through "a dozen mildewed books" and he thinks to himself "Shuyu doesn't know how to take care of books" and that he should give them to his nephews. In the last few lines of the passage, we see Lin sitting down on the grinding stone and flipping through his Russian dictionary. We can rightly conclude that the plot of the passage involves Lin sorting through some books and sitting outside his house. So, option B is the best answer. The other answers are incorrect because those choices are just passing mentions in the passage whereas the passage mostly focuses on Lin sorting through those books. Also, though Lin is fascinated by farm work, he doesn't know much about it (C). So, B is the answer.