(A) the forming of the Central Powers
(B) The sinking of the Lusitania
(C) the Zimmermann telegram
(D) ** the killing of Archduke Ferdinand
EXPLANATIONS BELOW
Concept note-1: -Two shots in Sarajevo ignited the fires of war and drew Europe toward World War I. Just hours after narrowly escaping an assassin’s bomb, Archduke Franz Ferdinand, the heir to Austro-Hungarian throne and his wife, the Duchess of Hohenberg, are killed by Gavrilo Princip .
Concept note-2: -The political objective of the assassination was to free Bosnia and Herzegovina of Austria-Hungarian rule and establish a common South Slav ("Yugoslav") state. The assassination precipitated the July Crisis which led to Austria-Hungary declaring war on Serbia and the start of World War I.
Concept note-3: -The assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, and his wife Sophie in Sarajevo (the capital of the Austro-Hungarian province of Bosnia-Herzegovina) on 28 June 1914 eventually led to the outbreak of the First World War.