求助一道逻辑题，谢谢

亲爱的敌人

Some species of dolphins find their prey by echolocation; they emit clicking sounds and listen for echoes returning from distant objects in the water. Marine biologists have speculated that those same clicking sounds might have a second function: particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload.

Which of the following, if discovered to be true, would cast the most serious doubt on the correctness of the speculation described above?

(A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.

(B) The usefulness of echolocation as a means of locating prey depends on the clicking sounds being of a type that the prey is incapable of perceiving, regardless of volume.

(C) If dolphins stun their prey, the effect is bound to be so temporary that stunning from far away, even if possible, would be ineffective.

(D) Echolocation appears to give dolphins that use it information about the richness of a source of food as well as about its direction.（B）

(E) The more distant a dolphin’s prey, the louder the echolocation clicks must be if they are to reveal the prey’s presence to the hunting dolphin.

这题为什么选B啊

Gkibt

题目重点：Dolphins use clicking noises to LOCATE their prey.Dolphins may use loud clicks to STUN their prey.
题目想表明的意思：biologists从dolphins角度出发，它的clicking除了locate prey功能以外，或许大声地clicking还有stun prey 功能。
问削弱

削弱的对象就是想办法不让stun这个功能实现。

A： 使用lecho 用来locate的海豚也会发出经常性的clikc在举例它prey很近的时候。选项看下来，我说不清是加强还是削弱，但我知道also这个词没有明显的反对或是削弱的意思，甚至更大的可能性是加强stun这个功能，所以排除。
B：depends on type 而不是 volume。这跟题目中说的 loud clikcs 不符，所以可以留着。
C：far away 这个词就可以把这选项排除了。题目里说的是stun是基于close range的功能。
D：题目想比较clicking与loud clicking 之间的功能，你告诉我关于食物是不是多和距离，这与我想要讨论的意思无关，排除。
E：先不说这选项意思是什么，看句子结构，the more。。。， the louder。。。是对于louder程度的扩大，不能说有加强的成分，但明显没有削弱loud这个因素的成分。再看句意，distant出现与题目讨论范围不一致（close range）排除

所以 选B

北纬53度

没做过GMAT题目，纯粹帮忙凑个热闹，见笑。B说这种定位方法捕猎者根本无法感知，那么又如何能够在近距离内吓唬捕食者呢（无法感知更加无法sensory overload了）？所以选B。其他选项读完要么无关要么能够佐证这种假设，所以不符。话说GMAT这题目真是长啊，读完花了半天

lisiberry

题干说了ecolocation的声音作用于鱼群，让它们无法承受感觉上的重负。因此可以帮助捕食。

b说其实这个声音别的生物听不见。-》如果是真的，如何解释其他鱼的感觉重负呢？=》因此削弱结论。