What do we learn about human casualties caused by war in history?
选项:
A:
Before the 20th century, the major causes of death were injuries and infection from wars.
B:
The number of soldiers who died in wars increased from the 19th to the 20th century.
C:
The percentage of soldiers who died during World War II is 48%.
D:
The targets of war have changed from soldiers only to civilians as well.