Ward notices that as his supply of marijuana decreases he starts thinking more and more about where he can get another supply as well as feeling nervous and anxious. this is an example of

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.