TOEFL Reading: ETS-TOEFL阅读机经 - JMPZ3D6319W4C58TL$

According to paragraph 6, how did public authorities respond to problems with the water supply during dry periods? A. They sent boats to fetch fresh water from nearby rivers B. They channeled river water into the cisterns C. They constructed an aqueduct D. They sold water from the cisterns in buckets to the public