详解
Choice C is the best answer. In the first paragraph, the third sentence describes the narrator's love of reading ("where my school friends saw notches of ink on incomprehensible pages, I saw light, streets, and people"), and the fourth sentence describes the role that reading played in the narrator's life ("a safe haven from that home, those streets, and those troubled days in which even I could sense that only a limited fortune awaited me"). The remainder of the passage recounts incidents in which the narrator's actions arise from his love of, and dependence on, reading. Thus the third and fourth sentences can be seen as describing a passion that accounts for those actions.
Choice A is incorrect because although the narrator's "school friends" are mentioned in passing in the third sentence, they aren't introduced as proper characters and make no further appearance in the passage. Choice B is incorrect because the passage doesn't list the difficult conditions of the narrator's childhood until after these sentences. Choice D is incorrect because the narrator’s aspirations aren’t discussed until the last paragraph of the passage.