Slovakia Was Never Part of Yugoslavia

Slovakia is the correct answer.

• Slovenia – Was a constituent republic of Yugoslavia (1945–1991).
• FYR Macedonia (now North Macedonia) – Was a constituent republic of Yugoslavia (1945–1991).
• Slovakia – Was part of Czechoslovakia (1918–1992); never in Yugoslavia. Peaceful "Velvet Divorce" created Czech Republic & Slovakia in 1993.

Yugoslavia's six republics: Slovenia, Croatia, Bosnia & Herzegovina, Serbia, Montenegro, Macedonia. Slovakia is Central European (Visegrád Group), not Balkan.