What caused austria-hungary to declare war on serbia, which eventually sparked world war i?

Tension had been growing between the European countries for sometime. Four causes that lead to the 'Spark' of the war were: Nationalism, Militarism, the causes that lead to the 'Spark' of the war were: Nationalism, Militarism, the Alliance-System, and Imperialism. On June 18, 1914, The Black Hand, and members of British and French Intelligence assassinate Franz Ferdinand, the archduke of Austria-Hungary. This sparks WW1. Outraged, Austria-Hungary wages war against Serbia. Thanks to the Alliance system, Austria drags Germany, (who wrongfully took the blame for the war), into the war. Serbia drags Russia into the war, making it a World War

Because the discoveries were some of the oldest human remains.