(A) militarism
(B) ** alliances
(C) imperialism
(D) nationalism
EXPLANATIONS BELOW
Concept note-1: -Countries that joined the Central Powers, such as Bulgaria and the Ottoman Empire, supported Austria-Hungary and Germany. The Allies were Russia, France, Belgium and Great Britain, but they were later joined by Japan, Romania, China and the United States.
Concept note-2: -World War I occurred between July 1914 and November 11, 1918. By the end of the war, over 17 million people would be killed including over 100, 000 American troops.
Concept note-3: -When World War I broke out, Italy was part of the Central Powers. But Italy stayed neutral and eventually switch sides to the Allies’ side. The alliance between Italy, Germany, and Austria-Hungary was always a shaky one at best.
Concept note-4: -The war pitted the Central Powers (mainly Germany, Austria-Hungary, and Turkey) against the Allies (mainly France, Great Britain, Russia, Italy, Japan, and, from 1917, the United States).