Respuesta :
I believe it's the assassination of Franz-Ferdinand, correct me if I'm wrong.
The assassination of Franz-Ferdinand is considered to be the "spark" which ignited World War I. Option C is correct.
Archduke Franz Ferdinand who was heir to the Austro-Hungarian Empire; was shot to death along with his wife Sophie by the Serbian nationalist Gavrilo Princip on June 28, 1914 in Sarajevo, Bosnia.
The assassinations sparked a chain of events that gave rise to the outbreak of World War I by early August.