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Although stepwise regression has reduced the model complexity significantly, the model still contains a lot of variables that we want to remove. Therefore, you are interested in lightweight linear regression models with ONLY TWO predictors. Write a script to automatically find the best lightweight model which corresponds to the model with the least rMSE on the training dataset. Compare the rMSE of the best lightweight model with the rMSE of the full model - lm.fit - that you built previously. Give an explanation for these results based on consideration of the predictors involved