Multiple choice Which event is most closely associated with the start of WWII in Europe assassination of Archduke Franz Ferdinand signing of the Munich Agreement invasion of Poland by Nazi forces building of the Berlin Wall Reveal answer Fill a bubble to check yourself C Correct answer Explanation The invasion of Poland on September 1, 1939, prompted Britain and France to declare war on Germany, marking the official start of World War II in Europe. The assassination of Archduke Franz Ferdinand started WWI, not WWII.