Final answer:
The clearest example of irredentism in Yugoslavia is the nationalistic efforts by Slobodan Miloševik to create a Greater Serbia by uniting all ethnic Serbs, which led to war and significant upheaval.
Step-by-step explanation:
The best example of irredentism in Yugoslavia is the efforts by Slobodan Miloševik in the early 1990s to create a Greater Serbia. Irredentism is a political movement that seeks to reclaim and reoccupy an area considered to be a lost territory of a nation. In the case of Yugoslavia, after the death of Josip Broz Tito in 1980, the nation began to unravel due to ethnic tensions and the decline of communism across Europe. Miloševik's aggressive nationalist policies aimed to unite all ethnic Serbs within the various provinces of Yugoslavia, including Kosovo and Montenegro, leading to armed conflict and eventual war. The quest for a Greater Serbia by Miloševik is one of the clearest examples of irredentism leading to significant political and social upheaval.