Answer:
World War I occurred because of a combination of both. Longtime rivalries over colonial divisions, trade and economic influence and domination existed among the great powers of Europe. For example, Germany resented having too few colonies and British superior naval force. They had also created a web of military alliances and defensive obligations - both public and secret - among themselves aimed at others. In the aftermath of duke FerdinandĀ“s assasination and the rapid succession of events, those factors contributed to dragging them into the war.
Step-by-step explanation: