The northern and southern polar regions are different in many ways. The most important dif

ference concerns the distribution of land and water. The northern Arctic regions are ice-covered sea, almost completely surrounded by land. The pole itself is in deep water. In the south, Antarctic is a huge continent which is surrounded by a great ocean. Because of this basic difference other differences occur. The Arctic has a varied climate, while the Antarctic climate varies little; the Arctic has much plant life, but the Antarctic is an empty desert. And whereas the Arctic has been exploited economically for centuries, trade has never really touched Antarctic. Interest in the Arctic began when America was discovered, and explorers tried to find a western sea route to India and China. In their search to find the "North-West Passage" the main problem facing the explorers was how to avoid the ice. One explorer, Nansen, found a unique answer to this problem. He intentionally became struck in the ice and traveled with it across the Arctic Ocean! But although many explorers tried, it was not until 1903 that the Arctic polar region was crossed by sea. Antarctic exploration begins with Ptolemy. He believed that all the oceans were surrounded by land, and therefore, there was huge continent somewhere in the south. His idea led to centuries of search, and again trade played its part. The real discoverers of Antarctic were the hunters who traveled far south to catch seals. One reason for the present interest in both polar regions is that world may soon be short of fresh water. In fact, over 85% of the earths entire fresh water is found in the polar ice. If we could find a way of carrying this ice to other parts of the world, this would solve all our fresh water problems.

Trade, according to the passage, has never really touched Antarctic because Antarctic is

A．a land surrounded by a great ocean

B．an empty desert and has no plant life

C．not open to public

D．different from the Arctic