Some species of dolphins find their prey by echolocation; they emit

Question

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 information about the richness of a source of food as well as about its direction.

(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.

Similar OG Question  :  LINK

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. Other toothed whales can produce high pitched clicks. When these clicks hit an object, some of the sound will echo back to the 'sender'. By listening to the echo and interpreting the time it took before the echo came back, the dolphin estimate the distance of the object.

mikemcgarry · Accepted Answer

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." Does that make sense? Let me know if you have any questions about this. Mike

KarishmaB · Answer

Some species of dolphins find their prey by echolocation; 
they emit clicking sounds and listen for echoes returning from distant objects in the water.

Speculation: 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.

We need to cast doubt on the correctness of the speculation. So we are looking for something that says that the clicking sounds may not serve this second purpose; they may not stun the prey.

(A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.
Irrelevant. Talks about how the clicks are used for prey location. Doesn't say anything about whether they are used for stunning too.

(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.

We know that the dolphins use echolocation to locate prey. This is given to us. This option tells us that echolocation can be used to locate prey only if the prey is incapable of perceiving the sound (Makes sense. If the prey perceives the sound, it will swim away from that location). Since the dolphins do use echolocation to local prey, it stands to reason then that the prey can't perceive the sound. If the prey cannot perceive the sound, how will they get a sensory overload? They will not be able to sense the sound at all. Hence, this option casts doubt on the speculation.

(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.

Irrelevant. The argument talks about stunning at close range. What happens from far away is irrelevant.

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

Irrelevant. Doesn't address the speculation at all.

(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.

Irrelevant. Doesn't address the speculation at all. It again deals with how echo sounds are used to locate prey. It doesn't say imply about stunning.

Answer (B)

BeckyRobinsonTPR · Answer

this is a weaken question so we have to determine the conclusion and premises first.

the conclusion of this argument is named as the speculation - that the clicking sounds might stun prey through sensory overload. 
the premise is that other toothed whales stun their prey with clicks.

To weaken an argument, you generally bring in new, relevant information, that shows that the conclusion is not necessarily true. So here we need to show that the clicking sounds are not used to stun. so an answer choice has to provide information that would mean this.

ramannanda9 · Answer

B it is, as the speculation by marine biologist is "particularly loud clicks might be used by
the dolphins to stun their prey at close range through  sensory overload ";

B says "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." if prey cannot perceive it how can the sensory overload take place ?

pavan2185 · Answer

What is the level of this question, according to your estimation?

pramendrapandeya · Answer

fact: Dolphins use clicking noises to LOCATE their prey. 
Conclusion: Dolphins use these same clicks to STUN their prey. 
To weaken the conclusion, the correct answer must BREAK THE LINK between the use of echolocation to LOCATE prey and the use of it to STUN prey.

Answer choice B breaks the link between the two:

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. 
The prey CANNOT BE STUNNED by clicks that it is INCAPABLE OF PERCEIVING, invalidating the conclusion that the dolphins use the clicks to stun their prey.

so answer is B.

JS1290 · Answer

mikemcgarry   GMATNinja   GMATNinja Two

Hi, I was wondering could one of you guys please explain why option E is incorrect? Our conclusion is "particularly loud clicks might be used by the dolphins to stun their prey at close range through sensory overload". E gives us an another reasoning which tells us that loud clicks may not be used to stun their prey at a  close range  but rather it is used to reveal a prey's presence. Please help me out and tell me where my reasoning is incorrect? Would greatly appreciate it!

GMATNinja · Answer

csaluja , choice (E) is tempting because, as you said, it gives an alternative explanation for the loud clicks.

However, keep in mind that the speculation/conclusion is NOT that the loud clicks are  only  used to stun prey at close range. Rather, the speculation is that the clicking sounds "might have a  second  function." So it's perfectly fine if loud clicks have TWO functions: 1) to locate distant prey (as described by choice E) and 2) to stun prey at close range.

If we were told that the loud clicks were ONLY used to locate distant prey, then the speculation would be contradicted. But, as is, choice (E) does not necessarily interfere with the speculation.

Choice (B) is a much better answer.

pk123 · Answer

Basically do you mean to say that clicking sounds being of a type that the prey is incapable of perceiving, regardless of volume ( in Option B) is equivalent to stunning the prey ( in premise). Effectively it means both mean only one function rather than 2 functions.

Appler · Answer

Situation: I t says that dolphins emit clicking sounds and listen for echoes returning from distant objects in the water. Based on this information, marine biologists have speculated that those clicks might be used by dolphins to stun their prey.
 Weaken:  All we have to do is to prove dolphins use the clicking sound NOT to stun their prey. They use the click only to measure the distance, or the prey can’t perceive the click.

(A) Dolphins that use echolocation to locate distant prey also emit frequent clicks at intermediate distances as they close in on their prey.
 This answer choice simply repeats the information given in the argument.

(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.
The click can’t be heard by dolphin’s prey, so it can be inferred that the prey won’t be stunned by the click.

(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.
We are not talking about the effectiveness of the clicking noise to its audience.

(D) Echolocation appears to give dolphins information about the richness of a source of food as well as about its direction.
This is an subjective response.

(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.
Still, we are not discussing about the volume of clicks. The arguments wants us to evaluate whether the click stun the prey or not!

akanshaxo · Answer

GMATNinja  
Can you explain why A is wrong?
I was stuck between A and B. I chose A.

MartyTargetTestPrep · Answer

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

(A) is a tempting trap, because when we read it we see a pattern, and may extend that pattern in a way that does not make complete sense.

In other words, from (A), we see that the dolphins use echolocation to locate distant prey, and that they continue to use it as they get closer to prey, and therefore, we may be tempted to decide that, even when they are at close range, they use the clicks for echolocation rather than for stunning prey.

This thinking is not supported, however.

Notice that choice (A) says nothing about what goes on when the dolphins are actually close to the prey. It says that they emit frequent clicks AT INTERMEDIATE DISTANCES as they CLOSE IN on the prey.

Yes, from what (A) says, we can tell that it is possible that dolphins use clicks for echolocation at close range, since they use clicks for echolocation at both long range an intermediate range. Even so, they may not use clicks for echolocation at close range, and further, even if they do use clicks for echolocation at close range, they may use them also to stun prey.

So, (A) does not clearly indicate anything about what goes on at close range, as opposed to a long or intermediate range, and does not say anything contrary to the speculation that, when close to prey, dolphins use loud clicks to stun the prey.

kratisrivastava · Answer

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 information about the richness of a source of food as well as about its direction.

(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.

Similar OG Question : LINK

Show Spoiler

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. Other toothed whales can produce high pitched clicks. When these clicks hit an object, some of the sound will echo back to the 'sender'. By listening to the echo and interpreting the time it took before the echo came back, the dolphin estimate the distance of the object.

shuklaji · Answer

VeritasKarishma Can you please comprehend the last line"Marine biologists .............through sensory overload".. Thank you

mSKR · Answer

Marine biologists have speculated-- speculated what?
 that 
 those same clicking sounds --those sounds 
might have a second function: have another function ,what function?
particularly loud clicks -- those loud clicks ,,which loud clicks (find their prey by echolocation)
 might be used -ok
by the dolphins - ok
to stun their prey - i see, to stun 
at close range--only at close range?
 through sensory overload.--through their sensory overload (overload--means passing signals intensity in excess)

biologists think these clicking sounds can also be used to stun their prey at close run by overloading sensory signals( sending signal intensity high)

what's question? == >Weaken this thought.

What B says:
(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.

echolocation is useful if prey can not perceive it how much ever the high intensity is . So it means if dolphins want to stun their prey they can not use these echolocation signals . so biologists claim can not be correct.
how much is the volume is irrespective

saby1410 · Answer

VeritasKarishma 
Please give your analysis of correct option B
I chose Option E but GmatNinja clarified that doubt above
Why E wrong

Is B correct becoz prey won't be able to listen echo and in conclusion told by goving high clicks dolphin will stun prey by  sensory overload  so sensory overload means attavking to senses
I'm confused please clarify

Posted from my mobile device

mSKR · Answer

My 2 cents here:

Argument says: Dolphins find their prey by echolocation
COnclusion : These echos could stun their prey at close range

How to weaken? 
echos don't tend to stun their prey

B says: due to this stun, prey may go away. So these echos stunning their prey doesn't make sense.
It means : You use something to catch . But if using this somethign can alert prey in advance then what's the use of even detecting?
Imagine: you want to kill mosquito, then you silent approach it . But if mosquito can easily stun your approach then your action of approaching become useless.

This is how I selected B:)

Hope it helps:)

Basshead · Answer

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

We need an answer choice that would weaken the idea that  'those same clicking sounds might have a section function: particularly loud clicks might be used by the dolphins to stun their pray at close range through sensory overload.'  Let's go through the choices.

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

We know that some species of dolphins find their prey by echolocation, emitting clicking sounds and listening for echoes from distant objects. Now, we're told they emit additional clicks at closer distances. Doesn't weaken the second function. A is out.

(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.

This choice tells us that echolocation only works IF the prey can't hear these clicks. If this was the case, then prey wouldn't be stunned by loud clicks. Keep this one.

(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.

We aren't discussing the effectiveness of the dolphin's stun -- we want to weaken the argument that dolphins emit loud clicks  in order to  stun their pray. C is gone.

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

Extra information. Out.

(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.

This choice doesn't really weaken the speculation of a second function. Dolphins use echolocation. The more distance a dolphin's prey, the louder these clicks must be. The suggestion of the second function is still intact here.

B is the best choice.

AbhishekDhanraJ72 · Answer

What does " regardless of VOLUME " mean in option B ? I crossed out the option bcs of this only. It's not VOLUME we are talking about rather we are talking about strength of sound. Expert please explain.

Posted from my mobile device

Posted from my mobile device

Some species of dolphins find their prey by echolocation; they emit

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Some species of dolphins find their prey by echolocation; they emit

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards