Which characteristic made world war ii different from previous wars?

a. the nations of europe united to fight against threats from asia and the americas
b. the economic cost of the war was lower due to the rejection of the total war philosophy
c. the weapons used to fight the war were based on extremely outdated technology
d. the death toll was substantially higher for both civilians and military forces

D. The death toll was substantially higher for both civilians and military forces

Explanation:

The Second World War was a global military conflict that took place between 1939 and 1945. In this, most of the nations of the world were involved, in fact at the time of the fall of the Hitlerian Reich, only nine States of the world were officially neutral. (Afghanistan, Denmark, Spain, Ireland, Mongolia, Nepal, Portugal, Sweden and Switzerland), including all the great powers, grouped in two opposing military alliances: the allies of the Second World War and the powers of the axis. It was the greatest war in history, with more than a hundred million soldiers mobilized and a state of "total war" in which the great contenders devoted all their economic, military and scientific capacity to the service of the war effort, erasing the distinction between resources civil and military. Marked by events of enormous repercussion that included the massive death of civilians, the Holocaust, the intensive bombing of cities and the one-time use of nuclear weapons in a military conflict, World War II was the deadliest in history. a result of between 50 and 70 million victims, 2.5% of the world population.

im not sure but i have a question for you?