A. international trade barriers
were lowered and unprecedented gains in efficiency
had been obtained through the use of automated robotic equipment in American manufacturing plants
(Sentence is in passive voice, passage in red is not parallel )B. America
lowered international trade barriers and
the use of automated robotic equipment in American manufacturing plants resulted in unprecedented gains in efficiency
(Sentence is in active voice, unnecessarily wordy and not succinct )C. international trade barriers
were lowered and unprecedented gains in efficiency
were obtained through the use of automated robotic equipment in American manufacturing plants
(Sentence is in passive voice, parallel structure )D. international trade barriers were lowered, obtaining unprecedented gains in efficiency through the automated use of robotic equipment in manufacturing plants of America
(unprecedented gains were not a result of low trade barriers, distorts the meaning)E. America lowered trade barriers internationally and the use of unprecedented automated robotic equipment in American manufacturing plants resulted in efficiency gains
(First part of the sentence in active voice, second in passive voice)
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