An Exclusively State Area of Government Regulation

An exclusively state area of government regulation:

A) concerns those internal matters where uniformity on a nationwide basis is essential.
B) permits state regulation is permitted if the Congress has expressly regulated the area.
C) includes situations in which the federal regulation of a subject matter is not comprehensive enough to preempt the field.
D) includes intrastate activities that do not have a substantial effect on interstate commerce.
E) concerns those subjects over which the federal government has preempted the field.