求助GWD-19-30一道逻辑题，想不出为什么

kellyfx

11.GWD-19-Q30
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?
A.        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.
B.        The first is a conclusion that the argument as a whole seeks to refute; the second is the main conclusion of the argument.
C.        The first is the main conclusion of the argument; the second is an objection that has been raised against that conclusion.
D.        The first is the main conclusion of the argument; the second is a prediction made on the basis of that conclusion.
E.        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.
答案为什么是D？

kellyfx

D说第一个黑体字是MAIN CONCLUSION，可是这明明是作者反驳的内容啊。是答案错了？还是我没想明白呢？谢谢了！

jhanas

正在看楼主写的托福贴，帮顶~~~~~~~~~