【正确答案】 C

【答案解析】本题为细节辨认题.由文章第二段"Some people on the earth do not get very much rain. Yet, they still do not become deserts. This is because there are some small green plants growing there. Plants help keep water in the earth. Plants do not let the wind blow the dirt away" 可以将A和B排除,而D文中没有提到,所以得出正确答案为C.