lsat-20-2-5

5. Immigration runoff from neighboring farms may well have increased the concentration of phosphorus in the local swamp above previous levels, but the claim that the increase in phosphorus is harming the swamp's native aquatic wildlife is false: the phosphorus concentration in the swamp is actually less than that found incertain kinds of bottled water that some people drink every day.

The argument is vulnerable to criticism on the ground that it (A) makes exaggerations in formulating the claim against which it argues (B) bases its conclusion on two contradictory claims (C) relies on evidence the relevance of which has not been established (D) concedes the very point that it argues against (E) makes a generalization that is unwarranted because the sources of the data on which it is based have not been specified.

答案是c ，但是c中的evidence the relevance of which has not been established ，体现在原文哪里呢？

ding

"but the claim that the increase in phosphorus is harming the swamp's native aquatic wildlife is false: the phosphorus concentration in the swamp is actually less than that found incertain kinds of bottled water that some people drink every day. "

the level of phosphorus concentration that harmful to people is irrelevant to the level harmful to the wildlife in the swamp. Certain concentration of phosphorus may be safe to human beings, but  deadly to the wildlife.

明白了 谢谢斑竹