These lines from Kennedy's 1963 Civil Rights Address seek to most clearly define which idea?

One hundred years of delay have passed since President Lincoln freed the slaves, yet their heirs, their grandsons, are not fully free. They are not yet free from the bonds of injustice; they are not yet free from social and economic oppression. And this nation for all its hopes and all its boasts will not be fully free until all its citizens are free. (5 points)

injustice
economics
freedom
nationality