By what legal code or precedent are powers not granted to the federal government reserved by the states?

Suppose a nation creates a brand new welfare program that provides free pre-school for children whose parents earn below the poverty level. This is likely to result in __________

a. calls by conservatives to cut taxes b. a sharp increase in the national debt c. an expansion of the government bureaucracy d. poor parents dropping out of workfare programs

A free trade agreement in which the free movement of labor, goods, and services is enforced is known as _____.

A. a free trade area B. a customs union C. a common market D. an economic union