(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 war started mainly because of four aspects: Militarism, Alliances, Imperialism and Nationalism. This is because big armies become potential threats to other countries, other countries started forcing alliances in order to secure land.
Concept note-3: -Following the assassination of Archduke Franz Ferdinand in Sarajevo in 1914, Wilhelm encouraged the Austrians to adopt an uncompromising line against Serbia, effectively writing them a ‘blank cheque’ for German support in the event of war. He appeared not to realise the chain reaction this would trigger.