Can someone help w this

Name three things the framers of the constitution did to keep the federal government or any part of it from becoming too powerful.

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.

Acase study allows a more detailed look at the life of a single subject than any other study