根据以下内容，回答题。 Passage Three Alaska， which was called Russian America before it was sold to U. S. A. ，joined the union as the forty-ninth state in 1959. Alaska is now the largest of all the 50 states of the U. S.. It was in 1867 that President A. Johnson's Secretary of State（国务卿） ，Seward bought Alaska from the Russians at a cost of 7.2 million. The buying of the huge northern land mass seemed at first something foolishly done. Not only was Alaska difficult to reach， but it was also hard to bye in， and it appeared to have no importance in time of war. Besides， there are volcanoes there as Alaska hes on the Pacific' ring of fire'. In Alaska large treeless areas are covered with snow all the year. For these reasons the buying of Alaska was called 'Seward's Fooly' at that time. However， in 1896 gold was found in Alaska， and people poured tin to the land quickly. Since then other important natural resources were discovered， including oil. Soon people changed their thinking about 'Seward's Fooly'. But most people visit Alaska in order to see the endless beauty of nature that the northern land discloses to them. For instance， there are a- bout 11，000 islands in Alaska. And in a certain area of Alaska the sun does not set for 82 days every year. Alaska belonged to__________before 1867. 查看材料 A.Russia