The unemployment rate in the United States fell from 7.5

The unemployment rate in the United States fell
from 7.5 percent in 1981 to 6.9 percent in 1986. It
cannot, however, be properly concluded from these
statistics that the number of unemployed in 1986
was lower than it had been in 1981 because-----.
(A) help-wanted advertisements increased between
1981 and 1986
(B) many of the high-paying industrial jobs avail-
able in 1981 were replaced by low-wage ser-
vice jobs in 1986, resulting in displacements
of hundreds of thousands of workers
(C) in some midwestern industrial states, the unem-
ployment rate was much higher in 1986 than
it had been in 1981
(D) the total available work force, including those
with and without employment, increased
between 1981 and 1986
(E) the average time that employees stay in any
one job dropped during the period 1981
to 1986