详解
Choice A is the best answer. The first paragraph explains the narrator's love of reading: "Even then my only friends were made of paper and ink. . . . Where my school friends saw notches of ink on incomprehensible pages, I saw light, streets, and people." The fourth paragraph reiterates this love in its description of the bookshop as a "sanctuary" and "refuge." The shift in focus occurs in the last six paragraphs, which recount the gift of a book that transforms the narrator's love of reading into a desire to write: "I did not think there could be a better [book] in the whole world and I was beginning to suspect that Mr. Dickens had written it just for me. Soon I was convinced that I didn't want to do anything else in life but learn to do what Mr. Dickens had done." Thus the passage's overall focus shifts from the narrator's love of reading to a specific incident that influences his decision to become a writer.
Choice B is incorrect because the passage never focuses on the narrator's father, who primarily serves to illustrate the narrator's determination to read books despite all obstacles. Choice C is incorrect because the passage focuses on the narrator's desire to write rather than on whatever skill he may have as a writer. Choice D is incorrect because the passage doesn't make the narrator's childhood hardships its central focus or analyze the effects of those hardships.