题目解析:
题干“根据第5段,农民如何应对日益增长的丝绸需求?”定位 As the demand for silk increased, peasant farmers replaced the fruit trees with mulberry trees (silkworms feed on mulberry leaves) and then began digging up even more rice paddies to expand this system.
随着对丝绸需求的增加,农民们用桑树(蚕以桑叶为食)取代了果树,然后开始挖出更多的稻田来扩大这一体系。故 B“他们把更多的稻田变成了桑树环绕的鱼塘”正确;A 错 cut down fruit tree 没提及;C 错他们在以前没有农业用途的土地上种上了桑树 no previous agricultural use 没提及;D 错,gave up fish farming 他们放弃养鱼,转而从事更有利可图的养蚕活动。