Which of the following countries was not a part of the Socialist Federal Republic of Yugoslavia?

The Socialist Federal Republic of Yugoslavia was the Yugoslav state in southeastern Europe that existed from its foundation in the aftermath of World War II until its dissolution in 1992 amid the Yugoslav Wars. It was made up of six socialist republics: Bosnia and Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia with Belgrade as its capital. The modern nation state of Albania emerged in 1912 following the defeat of the Ottomans in the Balkan Wars.