In 1974 the number of people employed in the U.S. steel industry was 521,000. By 2006 the total number of people employed had dropped to 156,000. Which of the following was a major contributing factor in the decreased employment and income in steel manufacturing?
(A) Increased tariffs on imported steel led to less foreign competition.
(B) Decreasing productivity per worker led to a decrease in labor demanded.
(C) The growth of high paying jobs in the service industry decreased steel wages.
(D) More processes were automated due to improvements in technology.