A Recent Change in the Typical U

A recent change in the typical U.S. density gradient has been

A) the elimination of the gap traditionally found in the center.
B) an increase in the extremes between the inner and outer areas.
C) an increase in the number of people living in the center.
D) a reduction in the differences in densities found within an urban area.
E) an increase in the differences in densities found within an urban area.