Question

What was “the spark” that ignited World War I? *
Assassination of Franz Ferdinand
Panama Canal being built
USS Maine explosion
Russian Revolution

Answer 1

The "spark" that ignited World War I was the "Assassination of Franz Ferdinand," since this set off a wide range of diplomatic repercussions due to an incredibly complex alliance system that existed within Europe at the time. 

Answer 2

Assassination of Franz Ferdinand was “the spark” that ignited World War I