阅读下面短文，从每题所给的四个选项(A、B、C、D)中，选出最佳选项。 The sandstorm has a bad effect on human beings, but it also brings some good results．There_ wouldn't have been our Chinese nation if there had been no sandstorms．Sandstorms have existed for millions of years, while the written history of human beings has lasted only 5, 000 years．The Loess Plateau(黄土高原)was formed by sandstorms over millions of years．The Yellow River, while moving through the Loess Plateau, carries a great deal of sand and has formed the North China Plain．The loess Plateau is regarded as the place where Chinese civilization(文明)began．If there had been no Loess Plateau, the North China Plain wouldn't have existed, nor would have the Chinese civilization． Sandstorms don't bring only loess to human beings．When sandstorms move from central A sia to the Pacific areas, they carry some minerals into the air, which will later fall into the ocean in the form of rain．The minerals will help some planktons(浮游动物)to live on．The planktons are eaten by small shell fish, and the fish live on these small shell fish, and fish are eaten by humans．This forms a biological chain which shows a relation between humans and nature． So it is unrealistic to say we should stop sandstorms．What we possibly do is to reduce their bad effect sd much as we can． | 
