What was a cause of World War I? the invasion of Belgium by German troops the unification of separate German states into one nation Russia's desire to stay out of military alliances Austria-Hungary's imperialist ambitions to dominate the Balkans

It would be Austria-Hungary's imperialist ambitions to dominate the Balkans, as they couldn't possibly stay a united country as there was many different languages and cultures which led to struggles for independence which led to the assassination of Archduke Franz Ferdinand by a Serbian terrorist organization