This question is incomplete because part of option D is missing; here is the complete question
Which event surrounding World War I had the greatest impact on Americans?
A. Germany attacking Belgium
B. The sinking of the Lusitania
C. Germany's boycott of imported goods
D. The assassination of Archduke Franz Ferdinand
The correct answer is B. The sinking of the Lusitania
Explanation:
On may 7th of 1915 Germany torpedoed an important British Ocean Liner known as the Lusitania RMS, this caused the sinking of the Lusitania near Ireland and the death of more than 1000 people. Besides this, the victims of this event included more than 100 U.S. citizens; this situation prompted the participation of the U.S. in the First World War as the U.S. government and citizens felt they needed to respond to the actions of Germany. Due to this, the sinking of the Lusitania was the even that had the greatest impact on the Americans.