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Assumption! Tufe Island

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Assumption! Tufe Island

by amysky_0205 » Sat Dec 22, 2012 9:14 pm
Two centuries ago, Tufe Peninsula became separated form the mainland, isolating on the newly formed Tufe Island a population of Turfil sunflowers. This population's descendants grow to be, on average, 40 centimeters shorter than Turfil sunflowers found on the mainland. Tufe Island is significantly drier than Tufe Peninsula was. So the current average height of Tufe's Turfil sunflowers is undoubtedly at least partially attributable to changes in Tufe's environmental conditions. Which of the following is an assumption on which the argument depends?

A. There are no types of vegetation on Tufe Island that are known to benefit from dry conditions.
B. There were about as many Turfil sunflowers on Tufe Peninsula two centuries ago as there are on Tufe Island today.
C. The mainland's environment has not changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago.
D. The soil on Tufe Island, unlike that on the mainland, lacks important nutrients that help Turfil sunflowers survive and grow tall in a dry environment.
E. The 40-centimeter height difference between the Turfil sunflowers on Tufe Island and those on the mainland is the only difference between the two populations.

OA: C

can someone explain this ?!?!?!
just can't figure it out... tks!
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Source: — Critical Reasoning |
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by aman88 » Sun Dec 23, 2012 12:19 am
Evidence + assumption = conclusion.

As soon as we understand the above equation, we can graphically imagine the scope of the argument.
1)Sunflowers on Tufe island
2)Sunflowers on Tufe Mainland

The argument is describing differences in the sunflowers on island and mainland and why there is a difference.

Lets work on the argument now:

Evidence: On Tufe island - Sunflowers are 40 cms 'shorter'. Climate is 'drier'.
Conclusion: The short height of sunflowers in the Tufe Island is due to changes in the environmental conditions there.

*notice the words shorter and drier. Those words show some comparison between the sunflowers of Island and the mainland. Therefore, the climate must be less dry on the mainland and sunflowers must be 40 cms taller.

In assumption CR questions, Negation Test works well(already explained before). Lets work on the answer choices and see how negating them affects the conclusion.

A. There are some types of vegetation on Tufe Island that are known to benefit from dry conditions. -> Does not affect the conclusion in any way. ELIMINATE
B. There were fewer Turfil sunflowers on Tufe Peninsula two centuries ago as there are on Tufe Island today. -> Does not affect the conclusion in any way. ELIMINATE
C. The mainland's environment has somehow changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago. ->After negating, it seems to refute the conclusion. ANSWER
D. The soil on Tufe Island, unlike that on the mainland, contains important nutrients that help Turfil sunflowers survive and grow tall in a dry environment. -> Does not affect the conclusion in any way. ELIMINATE
E. The 40-centimeter height difference between the Turfil sunflowers on Tufe Island and those on the mainland may not be the only difference between the two populations. -> Does not affect the conclusion in any way. ELIMINATE

Understand the basic equation of assumption CR questions. That's it.
Therefore, C.

Thanks.
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