What Factors Contributed to Making World War I "The Most

What factors contributed to making World War I "the most terrible war of all time"?

A) World War I involved all areas of the world, including South America, Africa, and Asia.
B) The use of trench warfare and new technology made conditions particularly horrible for soldiers.
C) A larger number of people died in World War I than any other war in history.
D) American propaganda campaigns demonized the enemy, fueling the war's label as "most terrible".
E) Food shortages on the home front led to many U.S. civilian deaths in addition to military deaths.