TOEFL Reading: ETS-TOEFL阅读机经 - A3GAK9_XILMZP804L$

Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. Peasants had to attach wheels to their plows to make it possible for their oxen to plow the heavy, wet soil of northern Europe. B. With speedy oxen pulling the plow, peasants were able to plow the heavy soil of northern Europe. C. Adding wheels to a plow made plowing the heavy soil of northern Europe much easier and potentially faster. D. Attaching wheels to a plow made it necessary to use speedier animals.