Part I: Multiple choice (5 points each) 1. Two straight line regression models have been proposed for the same response variable Y below. The first model uses x1 as a predictor, and the second model uses $2 as the predictor. In the following statements, RSS stands for residual sum of squares, and SSReg stands for the regression sum of squares, while subscripts stand for model numbers. Which of the following is true? 40 > 8 - 8 30 50 60 20 30 40 50 60 20 40 *1 x2 (a) RSS1 > RSS2, while SSRegi > SS Reg2 (b) RSS1 > RSS2, while SSRegi SSReg2 (d) RSS1