According to official data, more people were killed and killed during the First World War, in percentage terms, than in the case of World War II. According to estimates, tens of millions of people were killed as soldiers or as civilians, while many remained wounded or with permanent psychological consequences. Also economies of many countries have been largely destroyed, hundreds of billions of dollars have been spent directly in the war, and almost so indirectly. It was a war that cost more than any other war by then.
The answer is: C.