Looking for insight into the below practice query/answer. Thanks!

You are working as a consultant helping a retailer predict future sales based on historic data. You have created four different models, and to test your models you divided the data into a training and test set. You can find the RMSE of the different models in Table 21 Table 2: Error performance of different models on training and test sets # Variables RMSE of training set RMSE of test set Model 1 2.40% 2.70% Model 2 1.50% 3.20% Model 3 1.90% 2.60% Model 4 1.60% 2.80% (Select one correct answer.) (a) Model 1 is the best model because it has the smallest difference between the RMSE on the training and test set. (b) Model 2 is the best model because it has the lowest RMSE on the training set. (c) Model 3 is the best model because it has the lowest RMSE on the test set. 7 (d) Model 4 is the best model because the average RMSE of the training and test set is the lowest