TOEFL Reading: ETS-TOEFL阅读机经 - HX736YS5OQTR34XNL$

According to paragraph 3, growing grape vines and olive trees increased agricultural yields because A. grapes and olives were mostly used for trade rather than for competing with established crops in local markets B. grape vines and olive trees could be cultivated on land that was also used for raising sheep C. growing grapes and olives did not require the services of specialized workers D. grape vines and olive trees did not compete with other crops for land or labor