Which Statement Regarding the "Miracle" of War Production Is Most

Which statement regarding the "miracle" of war production is most accurate?

A) War production rested on the conversion of peacetime industries, so overall economic output grew
Very little.
B) Both corporate profits and personal incomes rose, though more-flexible smaller firms and wealthier individuals gained the most.
C) Worker productivity increased, due more to new job opportunities after a long depression than to any commitment to the war effort.
D) U.S. achievements in war production proved as important to the Allied victory as success on the battlefield.