[求助]could you help me to solve this problem?

yahoo750

Could you help me to solve this problem?
1)In a recent study on the connection between brain abvormalities and violent behavior, the researcher examined more than three hendred people who had engaged in unusually violent behavior toward friends and gamily members. In most of the people studied, the researcher found clues of brain abnormalities, including evidence of past brain injury and physical abnormality. The researcher concluded that evidence of brain abnormalities could be used to predict violent behavior.
Which of the following, if true would most seriously weaken the researcher's conclusion?
A) The incidence of brain abnormalities in the general population is as high as that in the group examined.
B) The brain abnormalities discovered in those studied are of two distinct kinds.
C) A wide variety of violent actions were exhibited by those studied.
D) Those studied in the experiment acted violently toward strangers as well as toward people they knew.
E) The study drew its subjects from a large geographical area.
The right answer is A, and could you tell me Why?[em07][em07]

mindfree

文章结论是说BA可以用于预测VB.A中说BA在其他所有人中的比例和此GROUP相同,说明BA不典型,有没有VB都大脑畸形.

yahoo750

Thank you very much

oddyuibe

同意
回家过年~

回家过年

还是排除法好！这题有些饶。
题目大概是精神病，暴力。结论精神病预测暴力，原因是调查300个暴力记录的人，这300人里大部分都有病。
A，说the incidence of brain abnormalities in the general population is as high as that in the group examined.总人数里面精神病发病率和这次调查的（300暴力人）一样多，说明正常人和暴力人有的精神病可能性是一样的，所以用精神病来预测暴力倾向行为不正确，削弱。