OG详解-OG2 文法 Q13

Choice D is the best answer. The sentence explains how the House of Wisdom preserved the world’s knowledge, noting that the library collected, translated, and printed writings from different countries. 
Choice A is incorrect. While the sentence indicates that the House of Wisdom was known for bringing together knowledge from around the world, it doesn’t explain how the library preserved this knowledge. Choice B is incorrect. The sentence makes a generalization about the scholars who were employed by the House of Wisdom; it doesn’t explain how the library preserved the world’s knowledge. Choice C is incorrect. The sentence identifies two authors whose writings were preserved at the House of Wisdom; it doesn’t explain how the library preserved the world’s knowledge.