Which Statement Is Most Accurate About the U

Which statement is most accurate about the U.S.between 1840-1860?

A) The per capita income of free people in the Southwest was about twice the national average.
B) The per capita income of free people in the entire U.S.decreased.
C) The per capita income of free people in the entire U.S.increased,but increased more slowly than it did before the Revolution.
D) The Northwest was the poorest part of the nation,as measured by per capita income of free people.