Answer:
Austria-Hungary
Step-by-step explanation:
Pan-Slavism before World War One would not have been very evident in "Austria-Hungary"
This is because even though, there is a minority speaker of Slavic language in Austria, the major language of Austrian people is German. Also, the major language of Hungry is Uralic in nature, with very little Slavic vocabulary.
Russia, Greece, and the Balkans language all rooted heavily in the Slavic language.
Hence, the correct answer, in this case, is "Austria-Hungary"