The correct answer is A) Austria-Hungary’s annexation of Bosnia increased ethnic tensions among Slavs in Bosnia and Herzegovina.
The statement that most accurately examines how the Balkans region factored into the outbreak of World War I was "Austria-Hungary’s annexation of Bosnia increased ethnic tensions among Slavs in Bosnia and Herzegovina.
And then, it happened. Austrian-Hungary Archduke Franz Ferdinand and his wife were assassinated on June 28, 1914, when they were visiting Bosnia. The Austria-Hungary Empire had annexed Sarajevo in 1908, that is why Ferdinand was visiting the territory to oversee the army in those lands. This assassination was one of the causes that started World War 1.