RC Guillemots are birds of Arctic Regions.

[soundok]

Guillemots are birds of Arctic Regions. They feed on fish that gather beneath thin sheets of floating ice, and they nest on nearby land. Guillemots need 80 consecutive snow-free days in a year to raise their chicks, so until average temperatures in the Arctic began to rise recently, the guillemots' range was limited to the southernmost Arctic coast. Therefore, if the warming continues, the guillemots' range will probably be enlarged by being extended northward along the coast.

Which of the following, if true, most seriously weakens the argument?
A. Even when the warming trend continues, there will still be years in which guillemot chicks are killed by an unusually early snow.
B. If the Arctic warming continues, guillemots' current predators are likely to succeed in extending their own range farther north.
C. Guillemots nest in coastal areas, where temperatures are generally high than inland areas.
D. If the Arctic warming continues, much of the thin ice in the southern Arctic will disappear.
E. The fist that guillemots eat are currently preyed on by a wilder variety of predators in the southernmost Arctic regions than they are farther north.

Ans: D

I chose B. I am not sure the why B is not correct. Is it wrong because the word "farther"?

[stock.mojo11]

Guillemots are birds of Arctic Regions. They feed on fish that gather beneath thin sheets of floating ice, and they nest on nearby land. Guillemots need 80 consecutive snow-free days in a year to raise their chicks, so until average temperatures in the Arctic began to rice recently, the guillemots' range was limited to the southernmost Arctic coast. Therefore, if the warming continues, the guillemots' range will probably be enlarged by being extended northward along the coast.

Which of the following, if true, most seriously weakens the argument?
A. Even when the warming trend continues, there will still be years in which guillemot chicks are killed by an unusually early snow.
B. If the Arctic warming continues, guillemots' current predators are likely to succeed in extending their own range farther north.
C. Guillemots nest in coastal areas, where temperatures are generally high than inland areas.
D. If the Arctic warming continues, much of the thin ice in the southern Arctic will disappear.
E. The fist that guillemots eat are currently preyed on by a wilder variety of predators in the southernmost Arctic regions than they are farther north.

Ans: D

I chose B. I am not sure the why B is not correct. Is it wrong because the word "farther"?

You might have gotten it down to B & D like I did. D trumps B because B is not negating the fact that G's range will not extend Northward. B is saying, G's predators will also go northward. So it might be that both G and its predators move north and few G survive. If that is the case, G did extend northward.

Whereas in D, the ice sheets will melt, G cannot stand on water as they did on ice sheets to pick the fish. If they try to do so, they risk and probably sink in water and die. If they dont do so, it is difficult to get food in the arctic and hence risk extinction. Forget expansion.

B T W, why are you naming these Q's RC and not CR?

[RonPurewal]

remember that you should BE LITERAL and STAY CLOSE TO THE CONCLUSION.

here's the CONCLUSION:

the guillemots' range will probably be enlarged by being extended northward along the coast.

both parts are important.
the orange part is important because IT IS A GIVEN THAT THE RANGE WILL EXTEND NORTHWARD.
therefore, the blue part boils down to this: WE WON'T LOSE THE SOUTHERN PART OF THE RANGE.
after all, it's a given that the range WILL extend northward (see orange part). therefore, if the conclusion is "the overall range will be greater", then this is DIRECTLY tied into preserving the existing southern part of the range. if you don't preserve that part, then the blue conclusion goes down the drain, even if we do extend the range northward.

B. If the Arctic warming continues, guillemots' current predators are likely to succeed in extending their own range farther north.

number 1, this has nothing whatsoever to do with the considerations cited above (i.e., preserving the existing habitat down south).

number 2, as the poster above has pointed out, an increase in the predators' habitat is directly linked to an increase in the guillemot habitat itself. if the predators are spreading, then that means there are guillemots in those regions into which they're spreading!

double bad.

D. If the Arctic warming continues, much of the thin ice in the southern Arctic will disappear.

this has everything to do with the considerations above, so it's the correct answer.

[gmatwork]

what do they mean by extension of the range?

[gmatwork]

can someone please explain this argument in simple words? what is given and what do we need to do to weaken the argument?

[RonPurewal]

can someone please explain this argument in simple words?

the argument:
* guillemots need a certain number of days without snow.
* so far, the only arctic regions with enough snow-free days have been at the southern extremes of the arctic.
* the northern parts of the arctic are warming up.
* therefore, guillemots will be able to live farther north.

what do they mean by extension of the range?

this means that they will be able to live farther up. ("range" = where they are able to live)

what is given and what do we need to do to weaken the argument?

i don't know what you mean by "what is given". what is given is what the argument says.
to weaken the argument, you have to show that the warming will work against the guillemots in some way.
they need thin sheets of ice (because they eat fish that gather underneath thin sheets of ice). therefore, if the thin ice sheets disappear, the guillemots won't be able to live in those regions anymore. if that happens, then the guillemots' range may move farther north, but it won't necessarily be enlarged.

[Aksy]

I found this question to be extremely tricky. Could an expert tell me what is the difficulty level of this question? i.e is this a 700-800 level question?

[StaceyKoprince]

I agree that this is a tricky one. Unfortunately, they don't release difficulty level data on any of their problems. I would guess that this one is in the high 600s to low 700s range, but I can't get more specific than that (and I may be wrong!). :)

[ankish]

This is a 700+ questions, 60-70% CR questions are easy at actual GMAT.

[jlucero]

This is a 700+ questions, 60-70% CR questions are easy at actual GMAT.

I think all of us struggle to figure out the true difficulty of a question, because it's not based on any one person's opinion, but what a large percentage of people are or are not able to do. On test day, it's not helpful to gauge the difficulty, but just do the best you can on each question you see and forget the question as soon as you hit submit.

[li.xi811]

Can someone please explain why (A) is wrong? Is it wrong because it has nothing to do with the range (where guillemots are able to live)?

Thanks in advance.

[RonPurewal]

Can someone please explain why (A) is wrong? Is it wrong because it has nothing to do with the range (where guillemots are able to live)?

Yeah.

"During some summers, Chicago has heat waves severe enough to kill babies."
--> This does not mean that Chicago lies outside of the human habitat.

Same here.

[li.xi811]

Yeah.

"During some summers, Chicago has heat waves severe enough to kill babies."
--> This does not mean that Chicago lies outside of the human habitat.

Same here.

Thank you, Ron.

[RonPurewal]

Sure.

[SydneyT842]

I know this question was answered a while back but I was wondering if someone could explain this to me. I reduced the answers down also to B & D however I picked B. Now, I felt like both answers relied on an assumption. I incorrectly picked B assuming that if the range of G's predators was extended, the G's would prefer not to inhabit a previously uninhabited area that now also contains their predators. But for D, wouldn't the assumption be that the G's can only catch the fish with the thin ice. I was under the assumption that the thin ice makes it easier since it pools the fish together (no pun intended) as opposed to being a requirement for the G's ability to catch their prey. If my assumption was true, it means that the southern coast would still be habitable but just the population would most likely decrease due to an increased difficulty of obtaining food.