A scientist discovers that the acidity of the lake increased over time. At the same time, it's population of minnows grew much smaller. When the acidity of the lake returned to normal, the minnow population recovered

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.