阅读一道，求解释。（已简化）

TheAssembly

此为一LSAT阅读题

A second achievement of the judicial system is the protection that has been provided against encroachment by the states into tribal affairs. Federal judges are not inclined to view favorably efforts to extend states powers and jurisdictions because of the direct threat that such expansion poses to the exercise of federal powers. In the absence of a federal statute directly and clearly allocating a function to the states, federal judges are inclined to reserve for the federal government—and the tribal governments under its charge—all those powers and rights they can be said to have possessed historically.

13.   It can be inferred that the author believes that the extension of the states’ powers and jurisdictions with respect to Native American affairs would be
                                        

答案：(D) detrimental to the interests of Native Americans

问：

1）从哪句话推出D?

2） 文中说因为such expansion poses threat to the exercise of federal powers.这个THREAT段落中指出了么？EXERCEISE OF FEDERAL POWERS是什么意思？它怎么威胁到这个POWERS的？

lisaluan

我觉得是首句推出了。

JS的第二个成就是为不让States 管tribal的事,提供了保护。这句话的态度比较明确。尤其是against encroachement by the states into tribal (Native Americans) affairs,中的against

法官们也不愿看见因可以运用的权利增长造成threat.如果没有FS明确直接的分配职能给state，FJ情愿保留FG--TG在他自己(its??)的掌下，。。。。