Which of the following has been mentioned by historians as a cause of World War I? nationalism in the Balkans militarism of African nations fighting between India and Pakistan an unprovoked attack on the U. S.

That would be nationalism in the Balkans. Prior to WWI, Austria-Hungary had annexed Bosnia and Herzegovina, angering many in the Balkans especially those who wished to see a unified Yugoslavia. One such group was the Young Bosnia revolutionary organization, whose membership included Gavrilo Princip, the man who assassinated Archduke Franz Ferdinand in 1914, thus starting WWI.