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 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.", 'The climatic effects of major volcanic eruptions can temporarily mask the general warming trend resulting from an excess of carbon dioxide in the atmosphere.', 'Three months after an early springtime eruption in South America during the late nineteenth century, sea surface temperatures near the coast began to fall.', 'There is a strong statistical link between volcanic eruptions and the severity of the rainy season in India.']