Between 1970 and 1980, energy consumption by United States industry peaked and then declined, so that by 1980 total industrial use of energy was below the 1970 level even though total industrial output had grown substantially in the same period. Industry must have instituted highly effective energy conservation measures in those years to have achieved such impressive results.

  Which of the following, if true, most seriously weakens the conclusion of the argument?

  (A) Many industries switched to the greatest extent possible from high-priced oil to lower-priced alternatives throughout the 1970&aposs.

  (B) Total residential energy consumption was higher in the United States in 1980 than it had been in 1970

  (C) Many industrial users of energy had paid little attention to energy conservation prior to 1970.

  (D) Industrial output grew less rapidly from 1970 to 1980 than it had from 1960 to 1970.

  (E) The industries whose production dropped sharply during the 1970&aposs included a disproportionately large number of energy-intensive industries.