The proportion of manufacturing companies in Alameda that use microelectronics in their manufacturing processes increased from 6 percent in 1979 to 66 percent in 1990. Many labor leaders say that the introduction of microelectronics is the principal cause of the great increase in unemployment during that period in Alameda. In actual fact, however, most of the job losses were due to organizational changes. Moreover, according to new figures released by the labor department, there were many more people employed in Alameda in the manufacturing industry in 1990 than in 1979.

Which of the following, if true, best reconciles the discrepancy between the increase in unemployment and the increase in jobs in the manufacturing industry of Alameda?

A:Many products that contain microelectronic components are now assembled completely by machine.

B:Workers involved in the various aspects of the manufacturing processes that use microelectronic technology need extensive training.

C:It is difficult to evaluate numerically what impact on job security the introduction of microelectronics in the workplace had before 1979.

D:In 1990 over 90 percent of the jobs in Alameda's manufacturing companies were filled by workers who moved to Alameda because they had skills for which there was no demand in Alameda prior to the introduction of microelectronics there.

E:Many workers who have retired from the manufacturing industry in Alameda since 1979 have not been replaced by younger workers.