Direction: Read the passage carefully and answer the given question.

In 1837 Louis Aggasiz, a young naturalist, had to suffer ridicule at the hands of geologists while trying to prove that the earth had gone through a number of ice ages. Then, for almost a century, the four-fold ice age scheme of the Alps (Wurm, Riss, Mindel and Gunz) given by Alberta Penck and E. B. Rucker in 1909 got so well entrenched in geology that most of the global evidence was forced to fit into this fourfold framework and nobody dared to think of more than four ice ages. Only recently have the data from sea-cores and deep ice cores revealed that, in the last 2 million years, the earth has witnessed 17-18 cold-warm oscillations rather than four, as believed earlier. More important was the realization that ice ages, were several times longer than the warm periods and that they could be triggered off even within a brief space of a century. The warm periods were normally only of a span of 10-15 thousand years. The portrait of an ice age is starkly gloomy. Vast areas of earth, including large areas of Europe, Canada, U.S.A and India: may come under a thick blanket of ice and the lower latitudes will be under the grip of droughts and famine. With the already mounting food and fuel crisis, the earth can ill-afford such a catastrophe.