The third alternative is correct (C).
In the 1980s, the Soviet Union confronted the US in the Cold War, where each country aimed to establish its economic model as dominant for the rest of the world. The US fought for capitalism and the Soviet Union for Communism.
The Soviet Union invested heavily in its military sector and in space technologies. However, the strength of the regime diminished as its production model collapsed. In this way, the mixing of the model of production in fall with high military expenditures and in other areas, made the Soviet empire crumble, giving the victory of the Cold War to the capitalism and the USA.