请教 OG CR 24题 题干的意思

24. If there is an oil-supply disruption resulting in higher international oil prices, domestic oil prices in open-market countries such as the United States will rise as well, whether such countries import all or none of their oil.
If the statement in the passage concerning oil-supply disruptions is true, which of the following policies in an open-market nation is most likely to reduce the long-term economic impact on that nation of sharp and unexpected increases in international oil prices?
A. Maintaining the quantity of oil imported at constant yearly levels
B. Increasing the number of oil tankers in its fleet
C. Suspending diplomatic relations with major oil-producing nations
D. Decreasing oil consumption through conservation
E. Decreasing domestic production of oil

不明白黑体字部分的 economic impact on 后面指代的 that nation of sharp and unexpected increases in international oil prices 是什么意思。

尤其是这个that 和 nation 各指的是什么？始终弄不明白

请各位大牛看的明白的指点指点。。。。

谢谢啦·！

我发现逻辑错题很多都是因为选项或者题干看的意思非常模糊。

open-market countries such as the United States will rise , whether such countries import all or none of their oil, If there is an oil-supply disruption resulting in higher international oil prices

A reduction in the amount of oil an open-market country consumes could reduce the economic impact of these increases.so,D is ture.

If the statement in the passage concerning oil-supply disruptions is true, which of the following policies in an open-market nation is most likely to reduce the long-term economic impact on that nation of sharp and unexpected increases in international oil prices?
明白了，实际上句子简化成这样就好读懂了。

If the statement in the passage concerning oil-supply disruptions is true，which of the following policies in an open-market nation is to reduce the impact? （The impact is attributed by ‘sharp and unexpected increases in international oil prices’ ）

终于弄懂了,sigh.语法结构不熟的缘故阿......哎。。。