After the WWII and the division into the interest zones, the countries of Eastern Europe fell under the influence of the Soviet Union. In order to spread the idea of communism and the world revolution, Stalin conducted so-called elections for governments in those countries. Those elections were undemocratic, and enforced in order to establish communist regimes under the watchful supervision of the Soviet emissaries. Many democratic representatives of the Eastern countries have been prevented in many ways from enforcing the will of voters. In order to strengthen his idea, Stalin resolutely cut off all the influence from the Western countries, and thus placed the Eastern countries behind the Iron Curtain.
The answer is: C.