Why does federalism create tension between state and national governments?
a. both national and state governments share power.
b. state and local governments have no support for national governments.
c. states are not able to work with each other.
d. the national government dominates the states.

Which statement is a good description of a model? a) models are a description of nature based only on one or two variables. b) models are testable ideas but they are not very to most people. c) models are a description of nature that predicts more accurately than real events. d) models are an approximiation of a real system that omits all but most essential variables in a system.