From which one of the following did Kosovo declare its independence ?

Kosovo issued a unilateral declaration of independence from Serbia on 17 February 2008. Authoritative contemporary accounts state this explicitly: BBC’s Kosovo profile records that Kosovo unilaterally declared independence from Serbia in February 2008 after prolonged tensions between its majority Albanian population and Serbian authorities [1]. The U.S. Office of the Historian/State Department likewise notes that Kosovo declared independence from Serbia on 17 February 2008 and refers to the international context and recognition debates that followed [2]. Since the declaration was a secession from Serbia (not from Bulgaria, Croatia, or Macedonia), the correct answer is option 4) Serbia.

Sources

1. [1] https://www.bbc.com/news/world-europe-18328859
2. [2] https://history.state.gov/countries/kosovo