What caused the United States to finally join the war in 1917?

Following archduke franz ferdinand's assassination, austro-hungarian leaders: a. aided the ottoman empire in its campaign to keep serbia under its control. b. executed nearly all prominent serbs living in austria-hungary c. threatened to invade serbia if serb leaders did not agree to a set of strict demands. d.. formed an alliance with great britain to protect austria-hungary from future attacks.

Under the new imperialism europe did not need large numbers of people to control territories because of

What was the main cause of the russian revolution? a. the protests against the war with poland b. the tremendous war losses of world war 1 c. the protests against the treaty of brest- litovsk d. the losses dictated by the treaty of versailles