Critical Reasoning

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 European 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 warning 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 El 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 temporarily 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 nineteenth century, sea surface temperatures near the coast began to fall.

The right answer doesn't have to disprove the argument; it only needs to make it less convincing. This is usually done by attacking assumptions or introducing new counter-premises. Since the only supporting evidence is a correlation between a previous eruption and a cold winter, the right answer will likely show that there is no causal link (perhaps something else caused the severe winter) or provide a counter-example (a big eruption that was not followed by a severe winter)

The right answer is C. I go through the question in detail in the full solution below (taken from the GMATFix App).



-Patrick

BlueDragon2010 wrote: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 European 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.

Summer of 1984 -

Eruption of Laki Volcano in Iceland ====> Unusually Severe winter

Hence -

Major eruptions cause atmosphere to become cooler than it would 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 warning of Pacific waters.

Out of scope of discussion.

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

Out of scope.

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

Contradicts the idea that severe winter as a result of an explosion.

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

Out of scope and Irrelevant.

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

Irrelevant.