(A) The sinking of the British passenger ship Lusitania
(B) The numerous alliances among countries in Europe
(C) ** The assassination of Archduke Franz Ferdinand
(D) The Japanese attack on Pearl Harbor in Hawaii
EXPLANATIONS BELOW
Concept note-1: -Archduke Franz Ferdinand of Austria and his wife Sophie are shot to death by a Bosnian Serb nationalist during an official visit to the Bosnian capital of Sarajevo on June 28, 1914. The killings sparked a chain of events that led to the outbreak of World War I by early August.
Concept note-2: -The assassination of Archduke Franz Ferdinand was the immediate cause of a war between two great powers-Russia and the Habsburg Austro-Hungarian Empire.
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.