Which of the following was a primary cause of World War I?

Militarism and alliances were indeed a primary cause of World War I. Prior to the war, European nations were engaged in an arms race, significantly increasing their military capabilities. This militaristic attitude contributed to a climate of tension and competition among countries. The formation of alliances further complicated this situation; major powers formed ententes and alliances, such as the Triple Alliance and the Triple Entente, which meant that any conflict involving one country could easily escalate into a larger war involving many nations.

This interconnected web of military agreements and rising nationalistic fervor ultimately created a situation where a conflict in one region, sparked by the assassination of Archduke Franz Ferdinand of Austria, triggered a domino effect, drawing in allied nations and leading to a full-scale war. The combination of militarism and the complex alliance systems established prior to the war were crucial in creating both the environment and the impetus for World War I.