What are 2 theories on why the cities of the mound builders disappeared

In his speech how does kennedy build his claim that the united states will defend freedom in its hour of maximum emergency? a. by arguing that the u. s. must enforce international law across the world since the united states is the lone superpower in the worldb. by demonstrating that the poverty which many people suffer from is an obstacle to true freedom  c. by stating that the u. s. will play an active role in fighting groups that are opposed to freedom, and by supporting groups that are fighting for freedom  d. by demanding that the adversaries of the united states be more willing to negotiate, or else there will be war

The crittenden compromise which option explains the role that this legislation played in the buildup to the civil war? it attempted to resolve the complications introduced by the missouri compromise; this to stave off the civil war. it sought to encourage southern diplomats to take their seats in congress so their voices could be heard in government. it proposed six amendments to the constitution aimed at protecting slavery; however, its passage was blocked by congress. it attempted to establish stipulations that made secession from the united states constitutionally legal.

Which of these is an edge city? boston, ma chicago, il irvine, ca detroit, mi