Differentiate between sources of the law?

Why is the supremacy clause considered to be the root of federalism?

47. when must a driver show proof of financial responsibility? a. when requested by a police office b. to register a vehicle or renew its registration c. to obtain a drivers education certificate d. both a and b

Which of the following powers is held only by the federal government? a. power to make a treaty b. power to set marriage laws c.power to create driving laws d.power to set the legal drinking age