请教大全20－2

大全-20-2.     
                    Mud from a lake on an uninhabited wooded island in northern Lake Superior contains toxic chemicals, including toxaphene, a banned pesticide for cotton that previously was manufactured and used, not in nearby regions of Canada or the northern United States, but in the southern United States. No dumping has occurred on the island. The island lake is sufficiently elevated that water from Lake Superior does not reach it.

The statements above, if true, most strongly support which of the following hypotheses?

(A) The waters of the island lake are more severely polluted than those of Lake Superior.

(B) The toxaphene was carried to the island in the atmosphere by winds.

(C) Banning chemicals such as toxaphene does not aid the natural environment.

(D) Toxaphene has adverse effects on human beings but not on other organisms.（B）

(E) Concentrations of toxaphene in the soil of cotton-growing regions are not sufficient of be measurable.

答案b，请问题目意思是什么啊？  怎么做啊！！没有看懂啊！谢谢！！！！！！！！！！