The correct answer is option 'D', which means that the Cold War refers to all of the above - tension between the Eastern Bloc and Western Bloc, ideological rivalry between the capitalist and communist world, and tension between the superpowers.

The Cold War was a period of geopolitical tension and ideological rivalry that lasted from the end of World War II until the early 1990s. It was primarily between the United States and its Western allies (Western Bloc) and the Soviet Union and its Eastern allies (Eastern Bloc). Here is a detailed explanation of each aspect:

Tension between Eastern Bloc and Western Bloc:
- After World War II, Europe was divided into two blocs, the Eastern Bloc led by the Soviet Union and the Western Bloc led by the United States.
- The Eastern Bloc consisted of countries under communist control, such as the Soviet Union, East Germany, Poland, Hungary, and Czechoslovakia, while the Western Bloc consisted of capitalist democracies, including the United States, United Kingdom, France, and West Germany.
- The tension between these two blocs arose from their opposing political and economic systems, as well as their conflicting interests and spheres of influence.

Ideological rivalry between Capitalist and Communist world:
- The Cold War was not just a conflict between two political and military alliances, but also an ideological rivalry between capitalism and communism.
- The Western Bloc, led by the United States, championed capitalism, democracy, and individual freedoms, while the Eastern Bloc, led by the Soviet Union, promoted communism, planned economies, and collective control.
- This ideological divide fueled conflicts and competition between the two sides, with each trying to expand its influence and ideology around the world.

Tension between Superpowers:
- The United States and the Soviet Union emerged as the two superpowers after World War II, and their competition for global dominance intensified the Cold War.
- Both superpowers engaged in an arms race, developing nuclear weapons and expanding their military capabilities.
- They also engaged in proxy wars, supporting opposing sides in conflicts around the world, such as the Korean War and the Vietnam War.
- The tension between the superpowers was characterized by espionage, propaganda, and a constant fear of a nuclear war.

In conclusion, the Cold War was a multifaceted conflict that encompassed tension between the Eastern Bloc and Western Bloc, ideological rivalry between the capitalist and communist world, as well as tension between the superpowers. These factors shaped the geopolitical landscape for several decades and had a significant impact on global politics.