Which of the following led to the Great War?

So the Great War (World War One) was a war that started in 1914 and finish on November 11, 1918. It lasted for four years.

Now the start of the war:

began in 1914 after the assassination of Archduke Franz Ferdinand of Austria. His murder catapulted into a war across Europe 

The U.S. didn't go into war for about 2 and an a half years, During the conflict, Germany, Austria-Hungary, Bulgaria and the Ottoman Empire (the Central Powers) fought against Great Britain, France, Russia, Italy, Romania, Japan and the United States (the Allied Powers).

By the time the war was over and the Allied Powers claimed victory, more than 16 million people—soldiers and civilians alike—were dead.

answer: hamilton

explanation: