Choose the correct statement or statements 1. An economic model is a description of some aspect of the economic world that includes only those features that are needed for the purpose at hand 2. Economists use natural experiments, statistical investigations, and economic experiments 3. An economic model is tested by comparing its predictions with the facts 4. An economic model must use events that arise in the ordinary course of economic life A. statements 1, 2 and 3 are correct O B. statements 2 and 3 are correct O C. statements 2, 3 and 4 are correct O D. statements 1 and 2 are correct