Final answer:
Before World War I, economic competition over colonial territories and resources was a major source of tension between European powers, particularly between Britain and Germany. The buildup of military strength and complex alliances also contributed to the pre-war tensions.
Step-by-step explanation:
Source of Tension Before World War I
One major source of tension between European powers before World War I was economic competition. As the European nations vied for colonial territories and resources, the quest for expansion and dominance heightened rivalries. The industrial revolution had significantly increased the economic and military potential of countries like Britain and Germany, leading to a competitive atmosphere over markets and resources. This economic competition was a critical factor contributing to the hostile environment that later developed into outright conflict during the war.
Germany's desire for increased colonial territories directly competed with the interests of the established British Empire. Moreover, the imperialistic ambitions of both countries and their allies led to a buildup of military strength, particularly in naval forces, setting the stage for what would later become World War I.
The alliances formed during this period also added to the tensions. The intricate web of treaties and agreements between nations ensured that a conflict between two could quickly expand to include their respective allies, as seen when the assassination of Archduke Franz Ferdinand eventually engulfed all major powers in the war.