This question relates to the College data set. (a) Split the data into a training set and a test set. Using out-of-state tuition as the response and the other variables as the predictors, perform forward stepwise selection on the training set in order to identify a satisfactory model that uses just a subset of the predictors. (b) Fit a GAM on the training data, using out-of-state tuition as the response and the features selected in the previous step as the predictors. Plot the results, and explain your findings. (c) Evaluate the model obtained on the test set, and explain the results obtained. (d) For which variables, if any, is there evidence of a non-linear relationship with the response?