What of the following describes an important cause of World War 1?

An important cause of World War I was the complex system of alliances that developed in Europe, which created a web of obligations among countries. Nationalism fueled tensions, as various ethnic groups sought independence and power, particularly in the Balkans. Militarism also played a significant role, as nations expanded their armies and navies, leading to an arms race. Finally, the assassination of Archduke Franz Ferdinand in 1914 acted as a catalyst, triggering the war amid these underlying tensions.