Answer Choice (c)

@Boram, Happy to help. When the author says, "No metals, other than the expensive, nonoxidizing gold, could be relied upon to give off positive-light reflections," the author is making a distinction between gold and other metals. You're right about that. But what is the distinction? The key word in this phrase is "nonoxidizing." Even if we don't know what this means, the passage provides context that allows us to figure out this term's meaning. First off, the last portion of the phrase in question tells us that gold, unlike the other metals, could be relied upon. That 's the first clue of what "nonoxidizing" means. We then are told about Noguchi's wishes in the next paragraph, as he wanted to make a purely reflective sculpture. At the end of the paragraph when discussing chrome-nickel steel, the author states, "Here, finally, was a permanently reflective surface, economically available in massive quantities." From this, we can infer that the nonoxidizing properties of gold were preferred by Noguchi because it somehow made gold more reliable, purely reflective, and permanently reflective. In the answer choices, we're looking for an answer that touches upon gold's ability to be more reliable, purely reflective, and permanently reflective than its other metal counterparts. Gold is preferred because it's long lasting and will remain reflective over time. Answer A is incorrect because it's not the direction we care about. We're primarily concerned with gold's ability to be permanently reflective (long lasting), and this answer doesn't touch upon that distinction. We can get rid of this choice. Answer B is incorrect because it fails to mention the key distinction of gold having greater reliability and permanence than its other metal counterparts. We can eliminate this choice. Answer C is correct; it properly captures the distinction the author is referring to because it describes metals that lose their reflective properties over time and a metal that does not lose its reflective properties over time. This is exactly why gold was better than the other metals—it was reliable and permanently reflective. This is our answer choice. Answer D is incorrect because it inaccurately states that the author is drawing a distinction between metal and nonmetallic materials. The author is comparing one type of metal (gold) with other types of metals. Answer E is incorrect because the distinction is not between highly reflective metals that were acceptable vs. experimental; rather, the distinction is between gold and its greater reliability and reflective permanence when compared to other metals. Does this make sense? Let us know if you have any more questions!