(A) Militarism
(B) ** Alliances
(C) Imperialism
(D) Nationalism
EXPLANATIONS BELOW
Concept note-1: -This increase in militarism helped push the countries involved into war. The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary.
Concept note-2: -The M-A-I-N acronym – militarism, alliances, imperialism and nationalism – is often used to analyse the war, and each of these reasons are cited to be the 4 main causes of World War One.
Concept note-3: -The most immediate cause was the assassination of Archduke Francis Ferdinand of Austria-Hungary. Austria-Hungary decided that Serbia was to blame for the assassination and declared war on Serbia. Before the assassination, there were other things going on in Europe that led up to the war.