Why were nations such as czechoslovakia, east germany, and austria hungary, and poland called satellite states of the soviet union

All these nations were considered as satellite states of the Soviet Union because they were ruled by communist leaders, influenced by the Soviet Union.

Explanation:

At the end of World War II, various countries of Eastern and Central Europe became influenced, politically and militarily, by the Soviet Union. Soviet troops remained in those countries after the end of the war, although some withdrew.

The States accused of being satellites of the Soviet Union were: Albania (in 1960 it would break with the Soviet Union), East Germany, Bulgaria, Czechoslovakia, Hungary, Poland and Romania in Europe and Mongolia in Asia. Yugoslavia was sometimes also described as a "Soviet satellite", although it distanced itself from the USSR after the Tito-Stalin break and subsequently helped form the Non-Aligned Movement. The People's Republic of Albania, under the leadership of the Stalinist Enver Hoxha, broke relations with the Soviet Union in 1960, after the Soviet de-Stalinization, these countries were all members of the so-called Eastern Bloc.

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation: