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A newborn kangaroo, or joey, is born after a short gestation period of only 39 days. At this stage, the joey’s hind limbs are not well developed, but its forelimbs are well developed, so that it can can climb from the cloaca into its mother’s pouch for further development. The recent discovery that ancient marsupial lions were also born with only their forelimbs developed supports the hypothesis that newborn marsupial lions must also have needed to climb into their mothers’ pouches.

The argument in this passage relies on which of the following assumptions?

[A] All animals that are born after a short gestation period are born with some parts of their bodies underdeveloped.
[B] Well developed forelimbs would have been more advantageous to ancient marsupial lions than well developed hind limbs would have been.
[C] If the newborn marsupial lion did not climb into its mother’s pouch, then paleontologists would be able to find evidence of this fact.
[D] Newborn marsupial lions that crawled into their mothers’ pouches could not have done so had they not had only their forelimbs developed at birth.
[E] Newborn marsupial lions would not have had only their forelimbs developed if this development were of no use to the marsupial lions.


Looking forward to your answers!

E
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option (D)

I will go with option E.

Evidences stated in the argument:

1. Joey is born after short gestation period
2. Joey's hind limbs are not well developed, but its forelimbs are.
3. The purpose of (2) is so it can climb into mother's pouch
4. Marsupial lions were born with only forelimbs developed

Argument implies:
"only lion's forelimbs were developed" ==> (implies) further development needed

Conclusion:
Hypothesis that newborn marsupial lions must have needed to climb into mother's pouches.

Answers: [E]

A. Nothing is mentioned about the gestation period of lion; We dont know if it is short or long. So "all animals" are born after short gestation period is not valid.

B. Nothing mentioned about the usage of hind limbs vs. forelimbs of lion in premises.

C. No discussion about paleontologist in the passage.

D. That newborn lions climbed into mother's pouches is conclusion. They had forelimbs developed at birth is evidence.There is no assumption in this answer choice.

E. This connects the evidence of developed forelimbs of joey with that of lion and ties to the conclusion that lions used these forelimbs to climb into mother's pouches. The assumption here is "what is the use of developed forelimbs if not needed to climb into mother's pouch". Hence this is the correct answer.

E

The answer is "B".
Premise 1. A newborn kangaroo, or joey, is born after a short gestation period of only 39 days.

Premise 2. At this stage, the joey’s hind limbs are not well developed, but its forelimbs are well developed, so that it can can climb from the cloaca into its mother’s pouch for further development.

Premise 3. The recent discovery that ancient marsupial lions were also born with only their forelimbs developed

Conclusion 1. The newborn marsupial lions must also have needed to climb into their mothers’ pouches

As concluded, the newborn marsupial lions must also have needed to climb into their mothers' pouches.....no problem so far.....but why premise 3. will support conclusion 1.
Premise 3. will only support conclusion if Well developed forelimbs would have been more advantageous to ancient marsupial lions than well developed hind limbs would have been.
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Test Description_______Date____Total___Quant_____ Verbal
GMAT PREP1_____________________610
GMAX online test 1____29.07.2011__540_____43________19
MGMAT CAT 1_________03.09.2011__580____42________28
MGMAT CAT 2_________02.10.2011__690____48________36
GMAX online test 2_____16.10.2011__640____48________32
MGMAT CAT 3_________23.11.2011__670____47________34
Veritas free CAT______ 31.10.2011___630___ 46________33
MGMAT CAT 4_________06.11.2011__690____48________36
MGMAT CAT 5_________13.11.2011__660____46________34
MGMAT CAT 6_________19.11.2011__680____51________33
GMAT PREP2__________23.11.2011__680
GMAT Exam___________24.11.2011__690____50________34

E

I would go with option E

-Deepak.

Correct Answer: (D)

Explanation: The conclusion is that the marsupial lions must have needed to climb their mother's pouch. Lets consider the choices one by one:
(A) For ancient marsupial lions, firstly, it is nowhere mentioned in the argument that they were born after a short gestation period. May be they were born with only fore limbs developed even after a long gestation period. Secondly, we don't need to assume that they were born with some parts underdeveloped as this is mentioned in the argument itself.
(B) Well developed forelimbs could well have been more advantageous than hind limbs to marsupial lions but for what purpose? May be for running but not necessarily for climbing their mother's pouch. Even if we assume that fore limbs were more advantageous, we cannot say that they were more advantageous for the purpose of climbing.
(C) It is clearly mentioned in the argument that it is an hypothesis that newborn marsupial lions must also have needed to climb into their mothers’ pouches. Paleontologists have no way to determine whether the marsupial lions actually did so or not.
(D) Lets assume that marsupial lions were born with their fore limbs AND hind limbs developed. Logically speaking, they must have been equally capable, if not more, of climbing their mother's pouch. But in the argument, the conclusion is based upon the development of ONLY the front limbs. So to reach the conclusion based upon the development of ONLY the front limbs, it is imperative to assume that the development of hind limbs must have reduced the capability of marsupial lions to climb into their mother's pouch.
(E) Again, the development of only the forelimbs could have been due to some purpose use but simply assuming this is not enough to conclude that the purpose was to climb into their mother's pouch.


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