Which factor played a major role in Austria-Hungary's decision to declare war on Serbia?
O A. Nationalists within Austria-Hungary believed all Serbs should be
part of their empire.
O B. Serbia was vulnerable due to its refusal to make alliances with
other European countries.
C. Serbia refused to negotiate with Austria-Hungary after Archduke
Ferdinand was killed.
D. Germany guaranteed Austria-Hungary its support in the conflict
with Serbia