Which statement is true about world war 1? a: the assassination of archduke francis ferdinand triggered the war. b: leaders prepared for a war by decreasing the size of their armies. c: social darwinism soothed some of the competition between the countries before the war. d: countries did not form alliances because it would force them to enter war.

It is A) The assasination of Archduke Francis Ferdinand and his wife caused uproar and the killings sparked a chain of events that led to the outbreak of World War I by early August. Basically Austria blamed Serbia (where this had happened) for deliberately instigating their murder because it was done by a nationalist.Austria asked for assurances that Germany would step in on its side against Russia and its allies, including France So later Austria-Hungary declared war on Serbia causing World War 1