In the United States, a Reason for the Increase of the Labor

In the United States, a reason for the increase of the labor force participation rate for women is that

A) there has been a decrease in jobs with flexible hours.
B) an increase in wealth allowed men to retire early.
C) improved Social Security benefits are available for women if they work.
D) more women pursued a college education and received higher wages upon graduation.
E) fewer women married.