Final answer:
The countries under dictatorships in Europe from 1917 to 1939 were Germany, Italy, Spain, Soviet Union, and Portugal, all of which transitioned into totalitarian regimes following the devastation of World War I.
Step-by-step explanation:
During the rise of dictatorships in Europe from 1917 to 1939, several countries found themselves under authoritarian rule. The correct answer to the question of which countries were under dictatorships during this period is (a) Germany, Italy, Spain, Soviet Union, Portugal. Each of these nations experienced a form of totalitarian government, with Italy under Benito Mussolini's fascist regime, Germany under Adolf Hitler's Nazi rule, the Soviet Union under Joseph Stalin's communist dictatorship, Spain under Francisco Franco, and Portugal under António de Oliveira Salazar.
The aftermath of World War I and the crises that followed paved the way for these leaders to rise to power, adversely rejecting democratic principles and promoting ideologies such as fascism and communism. Fascism was characterized by extreme nationalism, suppression of political opposition, and totalitarian controls over all aspects of life. Similarly, in the Soviet Union, communism under Stalin's totalitarian regime led to severe repression and the implementation of policies like forced collectivization that resulted in widespread famine.