LSAT-3-I-17 请教

The question whether intelligent life exists elsewhere in the universe is certainly imprecise, because we are not sure how different from us something might be and still count as “intelligent life.” Yet we cannot just decide to define “intelligent life” in some more precise way since it is likely that we will find and recognize intelligent life elsewhere in the universe only if we leave our definitions open to new, unimagined possibilities.

(A) showing the claim to be irrelevant to the issue at hand

(B) citing examples that fail to fit proposed definition of “intelligent life”

(C) claiming that “intelligent life” cannot be adequately defined

(D) arguing that the claim, if acted on, would be counterproductive（D）

(E) maintaining that the claim is not supported by the available evidence

ABE都可以通过无关词排除，可是在CD中一直是犹豫的，明明文章讲的更多的是“interlligent life is undefined",可是为什么答案确实D，"counterproductive",虽然我把它放回原文，的确能感觉到它没错，可是也没有办法排除C没错啊，所以请教NN们帮忙解答。

仔细看，C不是不好，还就是不对

Yet we cannot just decide to define “intelligent life” in some more precise way since.....

这句话强调的是 我们不能去DEFINE, 没有说我们能不能的问题，到底能不能, still a question. C说不能，PREMATURE

题干谈了两方面。

“yet”前说的是技术上不能定义（因为imprecise)，

“yet”后说的是策略上不应该定义。