[求助]GWD-19-Q30

hidenari

Criminologist:  Some legislators advocate mandating a sentence of life in prison for anyone who, having twice served sentences for serious crimes, is subsequently convicted of a third serious crime.  These legislators argue that such a policy would reduce crime dramatically, since it would take people with a proven tendency to commit crimes off the streets permanently.  What this reasoning overlooks, however, is that people old enough to have served two prison sentences for serious crimes rarely commit more than one subsequent crime.  Filling our prisons with such individuals would have exactly the opposite of the desired effect, since it would limit our ability to incarcerate younger criminals, who commit a far greater proportion of serious crimes.

In the argument as a whole, the two boldfaced portions play which of the following roles?

1. The first is a conclusion that the argument as a whole seeks to refute; the second is a claim that has been advanced in support of that conclusion.

2. The first is a conclusion that the argument as a whole seeks to refute; the second is the main conclusion of the argument.

3. The first is the main conclusion of the argument; the second is an objection that has been raised against that conclusion.

4. The first is the main conclusion of the argument; the second is a prediction made on the basis of that conclusion.

5. The first is a generalization about the likely effect of a policy under consideration in the argument; the second points out a group of exceptional cases to which that generalization does not apply.

能帮忙解释原文中的意思吗，谢谢

yubaiming

up

feifeizoe

Criminologist:  Some legislators advocate mandating a sentence of life in prison for anyone who, having twice served sentences for serious crimes, is subsequently convicted of a third serious crime.  These legislators argue that such a policy would reduce crime dramatically, since it would take people with a proven tendency to commit crimes off the streets permanently.  What this reasoning overlooks, however, is that people old enough to have served two prison sentences for serious crimes rarely commit more than one subsequent crime.  Filling our prisons with such individuals would have exactly the opposite of the desired effect, since it would limit our ability to incarcerate younger criminals, who commit a far greater proportion of serious crimes.

逻辑简图：

Premise: 立法者要对两次犯重罪的罪犯判以无期徒刑。理由：这些罪犯更可能三犯。
Conclusion1: 这个政策可以大幅减少犯罪行为。（被转折否定）

转折：它忽视了有些年纪很大的人犯了第二次之后，一般无法再犯第三次了。
Conclusion2：如此会使初衷无法实现。

因此选择B