Final answer:
The statement is true; military alliances that required mutual protection among European countries were a significant factor that led to the outbreak of the Great War (World War I).
Step-by-step explanation:
European countries indeed entered into military alliances that required mutual protection, which was a significant factor that caused the Great War, so the statement is true. By the early twentieth century, these alliances had created two opposed groups, with Germany, Austria-Hungary, and Italy forming the Triple Alliance, and France, Great Britain, and Russia forming the Triple Entente. The assassination of Archduke Franz Ferdinand by a Serbian nationalist was the spark that ignited the war, causing a domino effect due to these alliances. Each power was obligated to come to the defense of its allies, transforming localized disputes into a global conflict. The military buildups and rapid mobilization strategies of the time further decreased the window for diplomatic resolution, hastening the onset of World War