(A) 1911
(B) 1912
(C) 1913
(D) ** 1914
EXPLANATIONS BELOW
Concept note-1: -World War I began after the assassination of Austrian archduke Franz Ferdinand by South Slav nationalist Gavrilo Princip on June 28, 1914. Read more about why the Balkans became the “powder keg of Europe.”
Concept note-2: -July 28, 1914 Austria-Hungary declares war on Serbia, beginning World War I.
Concept note-3: -This year saw the beginning of what became known as World War I, after Archduke Franz Ferdinand of Austria, heir to the Austrian throne was assassinated by Serbian nationalist Gavrilo Princip.
Concept note-4: -The spark that set off World War I came on June 28, 1914, when a young Serbian patriot shot and killed Archduke Franz Ferdinand, the heir to the Austro-Hungarian Empire (Austria), in the city of Sarajevo. The assassin was a supporter of the Kingdom of Serbia, and within a month the Austrian army invaded Serbia.