13.Some anthropologists study modern-day societies of foragers in an effort to learn about our ancient ancestors who were also foragers. A flaw in this strat-egy is that forager societies are extremely varied. Indeed， any forager society with which anthropologists are familiar has had considerable contact with mo-dern nonforager societies.

　　Which of the following， if true， would most weaken the criticism made above of the anthropologists' strategy？

　　（A） All forager societies throughout history have had a number of important features in common that are absent from other types of societies.

　　（B） Most ancient forager societies either dissolved or made a transition to another way of life.

　　（C） All anthropologists study one kind or another of modern-day society.

　　（D） Many anthropologists who study modern-day forager societies do not draw inferences about ancient societies on the basis of their studies.

　　（E） Even those modern-day forager societies that have not had significant contact with modern societies are importantly different from ancient forager societies.

　　14.In a study of the effect of color on productivity，50 of 100 factory workers were moved from their drab workroom to a brightly colored workroom.Both these workers and the 50 who remained in the drab workroom increased their prod-uctivity， probably as a result of the interest taken by researchers in the work of both groups during the study.Which of the following， if true， would cast most doubt upon the author's inter-pretation of the study results given above？

　　（A） The 50 workers moved to the brightly colored room performed precisely the same manufacturing task as the workers who remained in the drab workroom.

　　（B） The drab workroom was designed to provide adequate space for at most 65 workers.

　　（C） The 50 workers who moved to the brightly colored workroom were matched as closely as possible in age and level of training to the 50 workers who remained in the drab work-room.

　　（D） Nearly all the workers in both groups had volunteered to move to the brightly colored workroom.

　　（E） Many of the workers who moved to the brightly colored workroom reported that they liked the drab workroom as well as or better than they liked the brightly colored workroom.