Which ideology was characterized by extreme nationalism and authoritarian rule after World War I?

Fascism is characterized by extreme nationalism and authoritarian rule, especially prominent in the interwar period following World War I. It promotes a centralized, dictatorial government, elevates the state above individual rights, and seeks to mobilize society in service of the national community. Fascist regimes, such as those in Italy under Mussolini and Germany under Hitler, emphasized national unity, militarism, and often sought to create a homogeneous national identity, leading to the suppression of dissent and the persecution of minority groups.

This ideology arose in response to the social and economic turmoil following World War I, where many countries faced instability, economic crises, and the threat of communism. The appeal of fascism lay in its promise to restore national pride and stability through authoritarian control. The other choices do not encapsulate the same combination of extreme nationalism and authoritarian governance that defines fascism. Democracy, for example, emphasizes individual freedoms and political pluralism, which contrasts sharply with the totalitarian tendencies of fascism. Similarly, socialism advocates for collective ownership and class struggle, diverging from fascist notions of nationalism and hierarchy. Libertarianism champions individual liberty and minimal government, which also stands opposed to the centralized control typical of fascist regimes.