Although a number of things brought about World War I, there was one event that pushed Europe over the edge. What was that event?

the October Russian Revolution

invasion of East Prussia by Russia

assassination of Archduke Ferdinand

the English naval blockade of Germany

The correct answer is C. Assassination of Archduke Ferdinand

Explanation

World War I was an armed conflict that took place in Europe during the early twentieth century in which empires such as Austro-Hungarian, Ottoman, German and Bulgarian were involved, who faced the United Kingdom, France, the Russian Empire, and the United States.

This conflict caused major changes in the political map of Europe and in international relations, especially in Europe. In addition, the event that marked its origin was the murder of the Archduke of Austro-Hungary Franz Ferdinand in Sarajevo because he was the heir of the Austro-Hungary Empire and as he was killed by Gavrilo Princip who was a Serbian the Austro-Hungary Empire declared the war and soon other countries organized in major powers. So, the correct answer is C. Assassination of Archduke Ferdinand

C is the right answer, that's the event that literally started the whole war