Answer:
C) rivalries among nationalities.
Step-by-step explanation:
The breakup of Yugoslavia during the 1990s was caused by rivalries among nationalities within the country, which had been brewing for years and were exacerbated by the fall of communism, economic difficulties, and political instability. The conflict was characterized by instances of ethnic cleansing and war crimes, particularly during the Bosnian War, but these were a consequence of the underlying rivalries among nationalities rather than a cause of the breakup itself. The assassination of the Archduke Franz Ferdinand in Sarajevo, NATO, and Russian espionage played a role in the conflict but were not primary causes.