Mayor: Migrating shorebirds stop at our beach just to feed on horsesh

Question

Mayor: Migrating shorebirds stop at our beach just to feed on horseshoe-crab eggs, a phenomenon that attracts tourists. To bring more tourists, the town council plans to undertake a beach reclamation project to double the area available to crabs for nesting.

Birdwatcher: Without a high density of crabs on a beach, migrating shorebirds will go hungry because shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest.

Which of the following, if true, would provide the mayor with the strongest counter to the birdwatcher’s objection?

(A) Every year a certain percentage of crabs are caught by fishermen as bait for eel traps.

(B) Horseshoe crabs are so prolific that given favorable circumstances their numbers increase rapidly.

(C) On average, tourists who come to the town in order to watch birds spend more money there than tourists who come for other purposes.

(D) The additional land made available by the reclamation project will give migrating shorebirds more space.

(E) Some of the migrating shorebirds make only one stop during their migration form South America to Canada

GMATPREP Code : VCR005663

KarishmaB · Accepted Answer

Responding to a pm:

This is what the argument says: 
Mayor' plan - Birds come to eat crab eggs at our beach. This brings tourists. So give crabs more area to lay eggs. (With the implication that more crabs may lay more eggs and bring more tourists)
Birdwatcher'a problem with the plan - Crab density should be high i.e. crabs per square foot of area should be more i.e. area should be less. When area is less, more crabs will accidentally uncover other crabs' eggs while digging their own nests. If more area is given to them, they will spread around and hence not uncover each other's nests by mistake. The birds will then not get to eat any eggs and they might stop coming.

Now we want to find the option that counters birdwatcher's problem. i.e. what can the mayor say which will resolve the problem posed by the birdwatcher? How can the mayor ensure more area for crabs and high crab density as well? 
B gives you the answer. Crabs are very prolific i.e. if you give them the right conditions, say more space, they will breed more and quickly fill up the space. So even if you increase the area available to them, they will increase their population such that the density of crabs will still remain high. Hence, it is the correct answer.

Maverick2008 · Answer

Ans B -- The discussion here is regarding reclaiming extra space by decimating crabs which in turn ,according to Birdwatcher may cause loss of horseshoe-crab eggs . This may dwindle the gathering of shorebirds . This in turn will impact the Moyer's reason to claim the space to attract more tourists . But if crab breed rapidly then Moyer reason can easily undermine Birdwatcher's comment.

FN · Answer

then your OA is wrong..this is straight up B

Nihit · Answer

OA is A , however it makes no sense .

hibloom · Answer

IMO B
So the argument here is whether the mayor's argument can be supported in light of the birdwatcher's argument. So mayor just offers the land. Birdwatcher says we need more such frogs. If we add B to mayor's argument i think we get it.

ritula · Answer

A????????No way! it must be B. whts the source?

icandy · Answer

Yeah! B clearly offers support to mayor by saying the HSC proliferate fast to cover the increase of the nesting area provided by the mayor and city.

A actually undermines the mayor's point by saying that HSC are taken away by FM. Also, it does not specify how much % of them are taken away. Lets say if the FM take 50%, it's a toast. If they take 1%, probably does not make much difference. We can't say for sure. So it can't be A

grumpyoldman · Answer

Where DO these things come from? Of course it is B. The birdwatcher's objection is that there must be a high DENSITY of crabs in order to attract the birds. He/she is assuming that an increase in the area of the beach necessarily reduces density. Choice B negates this assumption; it says that if beach area is increased, the crabs will multiply to fill it up.

ankit0411 · Answer

Please stay away from sources floating around the net.

This questions appears on the GMAT PREP as well.

The OA to the above question is B.

It's senseless to make discussions with a wrong OA.

Thanks,
Ankit

thienbinh · Answer

Clear B. Option A makes nonsense

jlgdr · Answer

This is B by POE and for the reasons mentioned above

jellybean23 · Answer

Even i opted for option B. But i feel A is the correct answer (though I am not sure) But this can be a possible explanation for A: Fishermen use Crabs as bait for eel trap every year and still migrating shorebirds stop at the beach just to feed on horseshoe-crab eggs. This implies that the high density of crabs on the beach is maintained. B mentions favorable circumstances which will be another assumption. Am I Wrong??? :roll:

KanupriyaS · Answer

I think A actually supports the Birdwatcher's objection. We are looking for something that counters his objection that 'Without a high density of crabs on a beach, migrating shorebirds will go hungry because shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest.'. If we assume A to be correct then it implies that fishermen use crabs ----> fewer crabs ----> fewer chances of uncovering eggs ----> migrating shorebirds will go hungry. We need something that contradicts this. B contradicts the birdwatcher's objection. favorable circumstances (already mentioned in the question stem that 'the town council plans to undertake a beach reclamation project to double the area available to crabs for nesting', hence we can expect the crab population to rise) ----> more crabs ----> more chances of uncovering eggs ----> more shorebirds will stop at the beach. This rightly counters the birdwatchers objection. Hope it clarifies your doubt. I tried my best to explain it. Kudos if you like

Good luck!!!

chetan86 · Answer

B will strenghen the argument of Mayor so IMO B should be the correct answer.

akhil911 · Answer

Found this explanation in beatthegmat thread and posting here :

This is a question that, upon first read, may seem vaguely illogical and abstruse. The key phrase is this: "shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest," which means that crabs dig their own nest, and thus accidentally uncover the eggs buried of nearby nests, and this is in fact what brings birds, which in turn brings tourists. This provides the link needed for the birdwatcher's argument; there must be a dense population of crabs for this accidental uncovering to occur; therefore, increasing the space in which crabs can nest will decrease the density, and decrease the number of accidental uncoverings. This is at the heart of the birdwatcher's argument.

However, there is a key assumption in the birdwatcher's argument: increasing the space for crab nesting will ONLY result in a decrease in crab density IF there is not a proportionate increase in crabs. In other words, if there were double the space, AND DOUBLE THE CRABS, the crab density would remain stable. We'd get more accidental egg uncovering, more birds, and more tourists; the birdwatcher would be wrong in her conclusion, and the mayor right.

Answer choice B reflects this logic, explaining that horseshoe crabs are both "prolific" and that their number increases rapidly given favorable circumstances (such as a beach reclamation project to give them extra space).

The other answer choices are mismatches. Choice A is about decreases, not increases, in crab population (and goes by percentage, which means that this situation would not change even if the population did). Choice C is about money, and far out of scope; the argument is about bringing more tourists, not about bringing more tourist money. Choice D is irrelevant and redundant: crabs have more space, so do birds- so what? Choice E discusses an irrelevant fact that has no direct bearing on the situation; we already know that birds stop here to get eggs, so we can safely assume they will continue to do so.

Following the thread of causation (in this case- crab density Arrow crabs uncovering eggs Arrow more birds Arrow more tourists) is key, here and on many CR questions.

Kudos me if you like the post !!!!!

mohnish104 · Answer

I dont know what source ur referring but the OA is B. Period.

arvind910619 · Answer

Imo B 
To weaken the conclusion of the bird watcher we have show that the density of horseshoe crab will not decrease .
B gives us reason for that

Poorvasha · Answer

B.
The increase in area or space will result in the crabs being spread out and they will not uncover each other's eggs accidently and thus the number of birds would reduce and consequently the number of tourists. This is the whole point of the birdwatcher's argument. However, if the density of carbs is high, then that coupled with an increase in area would lead to more eggs being uncovered and thus, more birds and tourist. This is exactly what B implies.

Sidraman57 · Answer

Mayor: Migrating shorebirds stop at our beach just to feed on horseshoe-crab eggs, a phenomenon that attracts tourists. To bring more tourists, the town council plans to undertake a beach reclamation project to double the area available to crabs for nesting.

Birdwatcher: Without a high density of crabs on a beach, migrating shorebirds will go hungry because shorebirds only eat eggs that a crab happens to uncover when it is digging its own nest.

Which of the following, if true, would provide the mayor with the strongest counter to the birdwatcher’s objection?

HAVE TO USE ELIMINATION METHOD :

(A) Every year a certain percentage of crabs are caught by fishermen as bait for eel traps. ### NO POINT ABOUT EEL ###

(B) Horseshoe crabs are so prolific that given favorable circumstances their numbers increase rapidly. ### ANSWER AS IT COUNTERS THE OBJECTION ###

(C) On average, tourists who come to the town in order to watch birds spend more money there than tourists who come for other purposes. ###IRRELEVANT ###

(D) The additional land made available by the reclamation project will give migrating shorebirds more space. ###TRUE###

(E) Some of the migrating shorebirds make only one stop during their migration form South America to Canada ###IRRELEVANT ###

Mayor: Migrating shorebirds stop at our beach just to feed on horsesh

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

Mayor: Migrating shorebirds stop at our beach just to feed on horsesh

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