Why were some Serbians and Bosnians angry with Austria-Hungary in 1914?

Austria-Hungary annexed Bosnia in 1908, taking control of a territory with many South Slavs, including Serbs. This angered some Bosnians and Serbians, who wanted greater independence or unity with Serbia. Choice A is the closest match, though Austria-Hungary had not taken over Serbia itself.

AI-written and checked against the verified answer.