The 19th century is usually labelled as the ‘long’ 19th century, this era has significant characteristics to mention. First, while the world had been geographically integrated into a single map by the end of the 18th century, the center of the international system appeared to be Europe (Hobsbawm, 1962:7). In this sense the major actors of the system were all European powers. Second, there was a tension between rulers and ruled throughout most of the century, which led to numerous mass movements, uprisings, and revolutions. Third, the century witnessed the rise of ideologies such as liberalism, nationalism, and socialism that reshaped the geographical and political borders of the European system. Fourth, the gap between absolutism and constitutionalism was a constant rivalry that challenged governments’ sovereignty. According to these information, the correct answer is option B.