GMAT逻辑题目Biometric access-control systems-those using fingerprints, voiceprints, etc., to regulate admittance to restricted areas-work by degrees of similarity, not by identity. After all, even the same finger will rarely leave exactly identic

GMAT逻辑题目Biometric access-control systems-those using fingerprints, voiceprints, etc., to regulate admittance to restricted areas-work by degrees of similarity, not by identity. After all, even the same finger will rarely leave exactly identic
GMAT逻辑题目
Biometric access-control systems-those using fingerprints, voiceprints, etc., to regulate admittance to restricted areas-work by degrees of similarity, not by identity. After all, even the same finger will rarely leave exactly identical prints. Such systems can be adjusted to minimize refusals of access to legitimate access-seekers. Such adjustments, however, increase the likelihood of admitting impostors.Which of the following conclusions is most strongly supported by the information above?
(A) If a biometric access-control system were made to work by identity, it would not produce any correct admittance decisions.
(B) If a biometric access-control system reliable prevents impostors from being admitted, it will sometimes turn away legitimate access seekers.
(C) Biometric access-control systems are appropriate only in situations in which admittance of impostors is less of a problem than is mistaken refusal of access.
(D) Nonbiometric access-control systems-based, for example, on numerical codes are less likely than biometric ones to admit impostors.
(E) Anyone choosing an access-control system should base the choice solely on the ratio of false refusals to false admittances.
为什么选B 而不是C 请高人指点

GMAT逻辑题目Biometric access-control systems-those using fingerprints, voiceprints, etc., to regulate admittance to restricted areas-work by degrees of similarity, not by identity. After all, even the same finger will rarely leave exactly identic
题干说B系统能够用指纹识别等方法控制门禁系统,但是这种识别只是识别指纹的相似性,而非真正的确定.毕竟,相同的手指也很少会留下完全相同的指纹.因此,这种系统可以被修改,以降低对合法进入者的拒绝概率.但是,这样却会提高非法入侵者进入的可能性.
问的是以下哪个选项被题干信息所支持.
B、如果B系统能够可靠的阻止非法入侵者进入,那么他有时也会拒绝合法进入者.这个说法是被题干支持的,因为这正好是题干说法的否定反推导,即题干的意思是：不拒绝合法者导致可能放入非法者,B选项的意思是：不放入非法者导致可能拒绝合法者.这个逻辑的推导过程是成立的.
C、B系统只有在非法进入者的危害性小于错误拒绝合法者的情况下才能使用.题目的意思并非比较这两者问题的严重性,而且,即便非法进入者有很大的危害,B系统也可以使用.因为题目并没有说那种情况下B系统不能用.因此,C选项不能得到题干信息的支持.