From the 1920s to the 1970s, about 1 out of 1,000 Americans was in prison at any point in time. By 2008, due largely to changes in drug laws and drug enforcement, that rate:

A. decreased to about 0.5 per 1,000.
B. increased to about 1.5 per 1,000.
C. doubled to about 2 per 1,000.
D.increased to about 5 per 1,000.