The unemployment rate in the United States fellfrom 7.5 percent in 1981 to 6.9 percent in 1986. Itcannot, however, be properly concluded from thesestatistics that the number of unemployed in 1986was lower than it had been in 1981 because-----.
(A) help-wanted advertisements increased between1981 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 displacementsof hundreds of thousands of workers
(C) in some midwestern industrial states, the unem-ployment rate was much higher in 1986 thanit had been in 1981
(D) the total available work force, including thosewith and without employment, increasedbetween 1981 and 1986
(E) the average time that employees stay in anyone job dropped during the period 1981to 1986
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