TOEFL Reading: ETS-TOEFL阅读机经 - L4DC4146JZ5X9SITL$

According to paragraph 3, what was one cause of the economic problems in Europe of the fourteenth century? A. Farming techniques produced insufficient amounts of food. B. Territories that farmers had begun to use for agriculture for the first time were disrupted by war. C. The technological improvements in farming made in earlier centuries were abandoned after 1300. D. Farming techniques used capital that was needed for investment in the development of technology.