问一道逻辑题 XDF Section 2-14

dandan74

A recent survey of all auto accident victims in doile County found that, of the severely injured drivers and front-seat passengers, 80 percent were not wearing seat belts at the time of their accidents. This indicates that , by wearing seat belts, drivers and front-seat passengers can greatly reduce their risk of being severly injured if they are in an auto accident.
The conclusion above is not properly drawn unless which of the following is true?
(A) Of all the drivers and front-seat passengers in the survey, more than 20 percent were wearing seat belts at the time of their accidents.
(B) considerably more than 20 percent of drivers and fornt-seat passengers in dole County always wear seat belts when traveling by car.
(C) More drivers and front-seat passengers than rear-seat passagers were very serverly injured.
(D) More than half of the drivers and front-seat passangers in the survey were not wearing seat belts at the time of their accidents.
(E) Most of the auto accidents reported to police in Dole County do not involve any serioius injury.

为什么答案是A呢,怎么也想不明白，这到题应如何入手呢?这种问 percentage的题有何规律吗?

helena220

我也不明白，我选的是C。请大家帮忙讨论一下。

dandan74

没有人帮帮忙吗?  C我是一开始就排除了，因为原文中没有提到rear-seat passagers，所以这是个新的概念，一般不对。

uclb5550

我理解选项一是说在调查中的人中，20%系安全带，暗示80%没系安全带的人和受重伤的80%基本上是交集。 所以能够支持结论系安全带能够降低车祸中受“重伤”的风险。 选项二把范围扩大到整个国家，并不能说明调查中的情况。 所以没说服力。