(A) Militarism
(B) Alliances
(C) Imperialism
(D) ** Nationalism
EXPLANATIONS BELOW
Concept note-1: -The first long-term cause of World War I is militarism. Militarism can best be understood as the buildup or expansion of the ability of a country’s military to wage war. In the decades before World War I many European countries began to practice militarism and worked to expand and strengthen their military forces.
Concept note-2: -Nationalism was closely linked to militarism. It fostered delusions about the relative military strength of European nations. Many living in the Great Powers considered their nations to be militarily superior and better equipped to win a future war in Europe.
Concept note-3: -A: It changed the world. It led to the Russian Revolution, the collapse of the German Empire and the collapse of the Hapsburg Monarchy, and it led to the restructuring of the political order in Europe and in other parts of the world, particularly in the Middle East.