TOEFL Reading: ETS-TOEFL阅读机经 - 3HFA4PVI6Q3J6723L$

Paragraph 2 suggests that irrigation increased the likelihood of destructive floods because A. irrigated fields were often in locations that tended to flood naturally B. the canal intakes for irrigation water often did not work C. most irrigation canals were too narrow and thus overflowed D. levees built to protect irrigation systems required maintenance