All of the following happened after the congress of berlin, except
a.
the balkan league attacked the ottoman empire.
c.
russia annexed serbia.
b.
austria annexed bosnia and herzegovinia.
d.
bulgaria lost land and power.

The best and most correct answer among the choices provided by your question is the third choice or letter C. 

After the Congress of Berlin, Austria annexed Bosnia and Herzegovinia.
Congress of Berlin, (June 13–July 13, 1878), diplomatic meeting of the major European powers at which the Treaty of Berlin replaced the Treaty of San Stefano, which had been signed by Russia and Turkey (March 3, 1878) at the conclusion of the Russo-Turkish War of 1877–78.

I hope my answer has come to your help. Thank you for posting your question here in We hope to answer more of your questions and inquiries soon. Have a nice day ahead!