The labor practices of the fast food industry have their origins in the assembly line systems adopted by American manufacturers in the early twentieth century. Business historian Alfred D. Chandler has argued that a high rate of "throughput" was the most important aspect of these mass production systems. A factory's throughput is the speed and volume of its flow-a much more crucial measurement, according to Chandler, than the number of workers it employs or the value of its machinery.

Which of the following choices best describes the evidence used in this excerpt?

An expert's opinion provides historical background of an important concept. An expert's viewpoint presents a counterclaim to the author's argument. Statistical and factual evidence prove the author's claim. Personal experience creates persuasive, emotional appeal.