What were the main causes identified for World War I?

The primary causes of World War I are well encapsulated by nationalism, militarism, imperialism, and the system of alliances. Nationalism fostered intense competition and rivalry among nations, as various ethnic groups sought self-determination and larger countries pursued national interests aggressively. Militarism contributed to an arms race, where nations stockpiled weapons and built up large militaries, leading to an environment ripe for conflict. Imperialism heightened tensions as countries competed for colonies and global dominance, exacerbating existing rivalries. The system of alliances created a network that meant local conflicts could escalate into a larger war, as countries were obligated to support their allies.

Other options focus on factors that, while they may have been influencing conditions of the time, do not capture the combination of elements that directly led to the outbreak of World War I as effectively as the chosen answer. The identified causes reflect a perfect storm of political and social dynamics that culminated in a global conflict, making it clear why this set of factors is considered the cornerstone of understanding the war's origins.