详解
Choice A is the best answer. In the passage, Lymie closes his book only after "a coat that he recognized as his father's was hung on the hook next to his chair" (lines 67-68,"through... chair"). It is Lymie's father's arrival that causes him to close the book.
Choices B, C, and D are incorrect because (lines 67-70,"through... coming") of the passage clearly establish that Lymie closes his book because his father has arrived, not that he does so because the party of four is too loud (choice B), because he has finished reading a section of the book (choice C), or because he is getting ready to leave (choice D).