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# The conclusion of the prompt is: "loud clicks might be

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Current Student
Joined: 12 Sep 2011
Posts: 899
Concentration: Finance, Finance
GMAT 1: 710 Q48 V40
The conclusion of the prompt is: "loud clicks might be [#permalink]

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03 Jan 2012, 12:00
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75% (01:26) correct 25% (02:27) wrong based on 4 sessions

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The conclusion of the prompt is: "loud clicks might be used by dolphis to stun their prey at close range through sensory overload". Your goal is to weaken this or prove it wrong. So the correct answer will most likely say something that means "The load clicks are used for a different reason, or in fact don't affect the prey at all"

The answer here is B. This choice shows that these clicks actually wouldn't be audible by the prey. If it's not audible then sensory overload could not occur. The trick here is that "Sensory Overload" applies to any of the 5 senses (smell, touch, taste, hear, sight) in real life. But in this prompt, it specifically refers to "loud clicks" so the sense here would only be hearing. So if the prey can't even hear the clicks, then they will have no effect on their senses, and they could not be stunned by the loud clicks at close range.

A) Out of scope. Uses the words "distant prey". This is out of scope b/c the prompt discusses prey at "close range"
B) B is correct b/c it weakens the conclusion. Since the clicks would not be audible at close range (or any range) the prey would not be stunned by "sensory overload". No "sensory overload" would occur from "load clicks" b/c they wouln't be able to hear it.
C) out of scope. Talks about "stunning from far away". The prompt only discusses and cares about "close range". Also out of scope b/c how long the prey would be stunned doesn't matter. We don't care about that detail.
D) Out of scope. This may be true, but does not do anything to weaken the conclusion. Totaly off topic.
E) This may be true, but is also out of scope. It doesn't matter how distant the prey is or how loud the click is. This is off topic and doesn't answer the prompt

I hope this helps!

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Magoosh GMAT Instructor
Joined: 28 Dec 2011
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03 Jan 2012, 12:01
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Hi, there! I'm happy to help with this.

Remember, in criticizing an argument, the most effective attack will be something that undercuts the assumption of the argument. The assumption is the unstated logical link between the premise and the conclusion. It is the underlying structure of the argument itself.

Here, the argument is:
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.

The conclusion is: "those same clicking sounds . . . might be used by the dolphins to stun their prey at close range through sensory overload."

One might imagine several assumptions for this argument. We are looking in the answer choices for something that plays that role: an unstated but necessary link to support the conclusion.

Notice answers (A) & (D) give additional facts. Additional facts outside the argument to some extent might support or detract from an argument, but if you want to "go for the jugular" in attacking an argument, you must attack the assumption, because the assumption is the underlying structure of the argument. This is always what the GMAT is asking you to do when it asks something like: "Which of the following, if discovered to be true, would cast the most serious doubt on the correctness of the speculation described above?" That's GMAT code for: attack the assumption of the argument.

Choice (E), rather than attack the argument, strengthens it. If the echolocation is louder, that will be more likely to induce the kind of "sensory overload" that would stun prey.

Choice (C) is talking about far away prey, whereas the argument for the stunning specifically focuses on prey "at close range." If you go back and read the prompt carefully, you will often find these precise little turns of a phrase that will simply invalidate certain answer choices.

By contrast, choice (B) singles out the assumption. If the echolocation is going to stun prey with "sensory overload", they have to be able to sense it in the first place! An animal can only experience sensory overload from something they are sensing in the first place. Statement (B) says the prey doesn't hear the clicks of echolocation --- that's a devastating blow to the argument about stunning through "sensory overload."

Mike
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Mike McGarry
Magoosh Test Prep

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Joined: 08 Aug 2011
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04 Jan 2012, 22:46
Speculation in this argument is that dolphins use their clicking to stun the prey and in order to weaken this speculation B is the strongest as it suggests that the dolphins would be successful if the prey is unable to here the clicking sounds as a result stunning is not possible.
Re: 16.10   [#permalink] 04 Jan 2012, 22:46
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