Yugoslavia
Austria
Ethnic Serbs wanted freedom for Bosnia, which the archduke rule.
Austria
The archduke Ferdinand was assassinated in Sarejevo in Bosnia/Herzegovina.
Austro-Hungary
Because Archduke Ferdinand disapproved of the Slavic people forming their own country. They were too afraid of him controlling the country. Also, Black Hand wanted independence for Slavic countries, and assassinating the Archduke got them attention. This was more likely to get them what they wanted (or so they thought).
the answer is A:austria-hungary
Serbia
Serbia
Austria
The city of Sarajevo, in Bosnia
Austria-Hungary.