(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.