Severe Winters - CR - Weaken

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Severe Winters - CR - Weaken

by Anshul Kapoor » Sun Apr 29, 2012 3:54 am
An unusually severe winter occurred in Europe after the continent was blanketed by a blue haze resulting from the eruption of the Laki Volcano in the Europeans republic of Iceland in the summer of 1984. Thus, it is evident that major eruptions cause the atmosphere to become cooler than it would be otherwise.
Which of the following statements, if true, most seriously weakens the argument above?

(A) The cooling effect triggered by volcanic eruptions in 1985 was counteracted by an unusual warming of Pacific waters.

(B) There is a strong statistical link between volcanic eruptions and the severity of the rainy season in India.

(C) A few months after EI Chichon's large eruption in April 1982, air temperatures throughout the region remained higher than expected, given the long-term weather trends.

(D) The climatic effects of major volcanic eruptions can temporality mask the general warming trend resulting from an excess of carbon dioxide in the atmosphere.

(E) Three months after an early springtime eruption in South America during the late 19th century, sea surface temperatures near the coast began to fall.

Can someone explain between choices 'A' & 'C'.

OA: C
Source: — Critical Reasoning |

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by GMAT Kolaveri » Sun Apr 29, 2012 5:34 am
Conclusion: major eruptions -------> the atmosphere to become cooler than it would be otherwise.

option C is one way to weaken it. When cause occured, the effect didnt occur.

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by ice_rush » Sun Apr 29, 2012 12:36 pm
(C) is the clear winner.

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by vk_vinayak » Sun Apr 29, 2012 8:52 pm
C clearly weakens the argument.

A, on the other hand, by saying that cooling effect was triggered by the eruption, strengthens the argument. The unusual warming of Pacific waters may not necessarily be due to the eruption.
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by agarwalmanoj2000 » Sun Apr 29, 2012 11:41 pm
Weaken: Major eruptions cause the atmosphere to become cooler.

Why not A?
(A) The cooling effect triggered by volcanic eruptions in 1985 was counteracted by an unusual warming of Pacific waters.

Counteracted means offset or neutralize, so option A means cooling effect was neutralize by xxx. It does not say anything about whether eruption cause cold, so this neither strengthen or weaken the argument.

Why C?
(C) A few months after EI Chichon's large eruption in April 1982, air temperatures throughout the region remained higher than expected, given the long-term weather trends.

Option C gives an example that eruption caused the atmosphere to become hot in place of hot, so this weakens the conclusion.

HTH