Why Did the Austrian Annexation of Bosnia and Herzegovina Cause

Why did the Austrian annexation of Bosnia and Herzegovina cause consternation in Belgrade?

A) The population in this area was ethnically related to the Serbs.
B) Serbia had now lost the majority of its soldiers.
C) The people of these areas were expected to plan a revolt against the Serbs.
D) Serbs began to think a different religion would be forced into the area.
E) The Serbs feared these areas would side with the opponent during conflict.