Mostly the reasons were economic. The country's economy was dismembered when it entered the great depression and they had to take care of that. The South used this to reinforce its values because nobody was bothering them since the great depression forced the government to move its focus on something else.
Ide have to say the second choice is the bests choice
During 1989 and 1990, the Berlin Wall came down, borders opened, and free elections ousted Communist regimes everywhere in eastern Europe. In late 1991 the Soviet Union itself dissolved into its component republics. With stunning speed, the Iron Curtain was lifted and the Cold War came to an end.