详解
The final sentence of the first paragraph makes clear that before adopting his daughter, the weaver Silas was greedy for gold and chained to his work, "deafened and blinded more and more to all things except the monotony of his loom." But after adopting Eppie, Silas became more interested in life outside his job: "Eppie called him away from his weaving, and made him think all its pauses a holiday, reawakening his senses with her fresh life." A major theme of the passage can be seen in this transformation, as it represents how loving a child can improve or change a parent's life.
Choice A is incorrect because even if the passage implies that Silas was too materialistic before his daughter's arrival in his life, his greediness was a personal characteristic only, not a societal one; whether the society Silas lives in is overly materialistic is never addressed. Choice B is incorrect because even if the passage represents the "moral purity" of children, it does so only indirectly and not as a major theme. Choice C is incorrect because the passage addresses childhood enthusiasm and curiosity more than "naïveté" and never discusses the length or "brevity" of that naïveté.