The answer is C. Because William Jennings Bryan who was heavily supported by populist during the election of 1896 said something about this during his "Cross of gold speech".
Answer:
C. The assassination of Archduke Franz Ferdinand in Sarajevo
Explanation:
As this assassination was done in Serbian territory, the Austrian-Hungarian government was extremely angered and used this event to bring Serbia into a fold. Obviously, Serbia did not accept the terms of Austria-Hungary and instead became allies with the Russian Empire.
If its Bill then its Arkansas
A massive topic for this could be oil. You could talk about OPEC and the different types of technologies involved