TOEFL Reading: ETS-TOEFL阅读机经 - ZF4XONP65631PYONL$

According to paragraph 5, what causes the crop yields in New England to fail A. The shift to livestock production by many farmers B. The decreased amount of time that fields were left fallow C. The practice of planting crops in the same field for three years in a row D. The reduced size of the average field