阅读下列短文，从下面每小题的A、B、C、D四个选项中选择最佳选项。

Sweden, officially the Kingdom of Sweden, is a country in Northern Europe. Sweden borders (与......接壤) Norway and Finland, and is connected to Denmark by a bridge-tunnel. At 450,295 square kilometers, Sweden is the third-largest country in the European Union by area, with a total population of about 9.6 million. Sweden has a low population density (密度) of 21 persons per square kilometer with the population mostly living in the southern half of the country. Southern Sweden is mainly agricultural, while the north is heavily forested.

      Sweden was discovered as an independent country during the Middle Ages. In the 17th century, the country became bigger to form the Swedish Empire. The empire grew to be one of the great powers of Europe in the 17th and early 18th centuries. The eastern half of Sweden, present-day Finland, was lost to Russia in 1809. The last war in Sweden was in 1814. Since then, Sweden has been at peace, remaining a largely neutral (中立的) nation. The country played a good role during World Wars I and II, taking in refugees (难民) from German occupied Europe. With the ending of the Cold War, Sweden joined the European Union.