The correct answer is option 4, Yugoslavia. Vojislav Kostunica was the President of Yugoslavia.

Option 1, Albania, is incorrect. Albania has had different presidents, and Vojislav Kostunica was not one of them.

Option 2, Bulgaria, is also incorrect. Bulgaria has had its own presidents, and Vojislav Kostunica was not one of them.

Option 3, Romania, is also incorrect. Similarly, Romania has its own presidents, and Vojislav Kostunica was not one of them.

Therefore, the correct answer is option 4, Yugoslavia. However, it is important to note that Yugoslavia no longer exists as a country. It dissolved in 2003 and was replaced by the countries of Serbia and Montenegro. Vojislav Kostunica served as the President of Yugoslavia from 2000 to 2003.

Alert - correct answer should be Serbia and Montenegro.