Consider the following provinces of former Yugoslavia : I. Bosnia II. Croatia III. Slovenia IV. Yugoslavia. The correct sequence of these provinces from the east to the west is

Among the listed units, the easternmost is the area represented by “Yugoslavia” (here referring to the Serbia-dominated eastern part), followed westward by Bosnia, then Croatia, and finally Slovenia as the westernmost. Source material notes that Bosnia is bounded on its east and southeast by Serbia/Montenegro (i.e., the Yugoslav/Serbian area) and on its west by Croatia, placing Serbia (Yugoslavia) east of Bosnia and Croatia to Bosnia’s west. It also describes Slovenia as lying to the northwest/west of Croatia and adjacent to the Adriatic, making Slovenia the westernmost of the four. The general listing of the former Yugoslav republics in regional maps further supports this east-to-west ordering: Yugoslavia (Serbia) → Bosnia → Croatia → Slovenia [1].

Sources

1. [1] https://www.britannica.com/place/Yugoslavia-former-federated-nation-1929-2003