The correct answer is many men were pressed into military service overseas.
Once the United States entered World War II, the US instituted a military draft. This resulted in millions of men being chosen to join the US military at this time. These men left behind jobs that needed to be filled, as businesses were heavily increasing the production of goods for the war effort. This resulted in the drastic increase of women in the workforce. This increase in women in the workforce was further encouraged by propaganda such as Rosie the Riveter.
