(A) ** Militarism, alliances, imperialism, nationalism
(B) Machines, anarchy, industry, narcotics
(C) Medulla, amygdala, inferior temporal gyrus, neural network
(D) Monkeys, aardvarks, insects, narwhals
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.