The correct answer is "Control of the Balkan States".
Political instability in the region of the Balkans, which comprises Bosnia and Serbia and Herzegovina was the prelude for what would later become the First World War. Archduke Franz Ferdinand, heir to the Austro-Hungarian empire was assassinated in Serbia in 1914. This was interpreted as an explicit declaration of Serbian "nationalism" and an intention to separate from the Austro Hungarian Empire. After Russia sided with Serbia, Germany decided to ally with the Austro Hungary, initiating the first World War.