You fit two models (a and b) to the same data, and the following statistics for the training and validations sets are reported. You will pick the best performing model. Which model do you select, a or b? Training set: RSquare = 0.9, RMSE = 1.5 Validation set: RSquare = 0.5, RMSE = 2.0 Training set: RSquare = 0.8, RMSE = 1.7 Validation set: RSquare = 0.7, RMSE = 1.8