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# Last winter was mild enough to allow most bird species to forage natur

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Manager
Joined: 22 Jun 2017
Posts: 168
Location: Argentina
Schools: HBS, Stanford, Wharton
GMAT 1: 630 Q43 V34
Last winter was mild enough to allow most bird species to forage natur  [#permalink]

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10 Feb 2019, 19:31
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Difficulty:

55% (hard)

Question Stats:

60% (01:58) correct 40% (02:27) wrong based on 120 sessions

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Last winter was mild enough to allow most bird species to forage naturally, which explains why the proportion of birds visiting feeders was much lower than usual. The mild winter also allowed many species to stay in their summer range all winter without migrating south, thereby limiting the usual attrition accompanying migration. Hence, last year’s mild winter is responsible for this year’s larger-than-usual bird population.

Which one of the following, if true, would most strengthen the reasoning in the argument?
(A) Increases in bird populations sometimes occur following unusual weather patterns.
(B) When birds do not migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate.
(C) Birds eating at feeders are more vulnerable to predators than are birds foraging naturally.
(D) Birds that remain in their summer range all winter often exhaust that range’s food supply before spring.
(E) Birds sometimes visit feeders even when they are able to find sufficient food for survival by foraging naturally.

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Joined: 15 Jan 2019
Posts: 13
Re: Last winter was mild enough to allow most bird species to forage natur  [#permalink]

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10 Feb 2019, 19:37
Hello, why Is C the right answe?
In the passage, there is not mention of predators, is talking about the weather change patterns

Posted from my mobile device
Manager
Joined: 22 Jun 2017
Posts: 168
Location: Argentina
Schools: HBS, Stanford, Wharton
GMAT 1: 630 Q43 V34
Last winter was mild enough to allow most bird species to forage natur  [#permalink]

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Updated on: 10 Feb 2019, 20:36
1
1
RaquelR1409 wrote:
Hello, why Is C the right answe?
In the passage, there is not mention of predators, is talking about the weather change patterns

Posted from my mobile device

Hi!
The question says "which one of the following, if true,...

I think that to answer this question is important to consider the "if true" part, because that is signaling that all answer choices can be true..

Apart from that, we want to strengthen the conclusion, which says "Hence, last year’s mild winter is responsible for this year’s larger-than-usual bird population". In other words, we want to say that the weather caused the larger than usual bird population.

With that in mind, let's consider now the premise that supports the conclusion: "Last winter was mild enough to allow most bird species to forage naturally(cause), which explains why the proportion of birds visiting feeders was much lower than usual (effect)".

We want to say that the cause stated is in fact the cause of the effect and not another cause. Then (C) fits in perfectly. C says
"Birds eating at feeders are more vulnerable to predators than are birds foraging naturally," then as this winter allows the birds to forage naturally, birds won't eat at feeders where they are more vulnerable to predators. Since predators kill birds and since birds don't go to where the predators are because the weather allows them to do so, their population is larger than usual.

I hope it helps.
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Originally posted by patto on 10 Feb 2019, 19:54.
Last edited by patto on 10 Feb 2019, 20:36, edited 1 time in total.
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Posts: 193
Re: Last winter was mild enough to allow most bird species to forage natur  [#permalink]

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10 Feb 2019, 20:08
RaquelR1409 wrote:
Hello, why Is C the right answe?
In the passage, there is not mention of predators, is talking about the weather change patterns

Posted from my mobile device

Hello,
Let me explain how C is the right answer.
It is a strengthen question so we can bring outside information.
The argument says:
The mild winter allowed birds to collect food naturally rather than visiting feeders.Also the mild winters prevented the birds from migrating south.
The argument says these two factors are responsible for larger than usual bird population this year.

So we need to strengthen it.So we need to prove that these two factors only are responsible for the increase ,using the outside info.

Now C says :

There are more predators in feeders than natural environment so there are more chances of them being killed in feeders and since they did not go to feeders this year,there is less probability of them getting killed so

mild winter--less visit to feeders--so less attacks--so more population thus mild winter is responsible for population.

We need to fill in the reasoning gap.

mild winter---more population.

Fill this gap:

Here assumption is vulnerability will lead to death but since no other option fits in,C makes perfect sense.
Hope this helps.
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Joined: 16 Oct 2010
Posts: 9701
Location: Pune, India
Re: Last winter was mild enough to allow most bird species to forage natur  [#permalink]

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11 Feb 2019, 01:41
1
1
patto wrote:
Last winter was mild enough to allow most bird species to forage naturally, which explains why the proportion of birds visiting feeders was much lower than usual. The mild winter also allowed many species to stay in their summer range all winter without migrating south, thereby limiting the usual attrition accompanying migration. Hence, last year’s mild winter is responsible for this year’s larger-than-usual bird population.

Which one of the following, if true, would most strengthen the reasoning in the argument?
(A) Increases in bird populations sometimes occur following unusual weather patterns.
(B) When birds do not migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate.
(C) Birds eating at feeders are more vulnerable to predators than are birds foraging naturally.
(D) Birds that remain in their summer range all winter often exhaust that range’s food supply before spring.
(E) Birds sometimes visit feeders even when they are able to find sufficient food for survival by foraging naturally.

Premises:

Last year's mild winter led to more natural foraging and less feeder visiting.
Last year's mild winter also led to no migration and hence limited the accompanying reduction in numbers.

Conclusion: Last year’s mild winter is responsible for this year’s larger-than-usual bird population

We need to strengthen that mild winter is the reason behind larger than usual bird population right now.

(A) Increases in bird populations sometimes occur following unusual weather patterns.

We need to strengthen that mild winter led to increase in bird population. We don't know what unusual weather pattern is being talked about here. Also, we are given that SOMETIMES unusual weather pattern leads to increase. Is it one of those times, we don't know.

(B) When birds do not migrate south, the mating behaviors they exhibit differ from those they exhibit when they do migrate.

We don't know how the mating behaviour differs. Do they multiply faster or slower? - Does not tell us.

(C) Birds eating at feeders are more vulnerable to predators than are birds foraging naturally.

This tells us that birds foraging naturally are less likely to be killed by predators. We know that mild winters led to more natural foraging and less feeding at feeders. So this helps strengthen that mild winters led to a higher bird population this time.

(D) Birds that remain in their summer range all winter often exhaust that range’s food supply before spring.

Irrelevant. What will happen in spring is not our concern.

(E) Birds sometimes visit feeders even when they are able to find sufficient food for survival by foraging naturally.

Doesn't help strengthen our conclusion. Even if some birds visited feeders, the number was less than before and that the argument tells us. It doesn't help connect mild winter with increase in bird population.

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Re: Last winter was mild enough to allow most bird species to forage natur   [#permalink] 11 Feb 2019, 01:41
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