2. [3 points] Is each statement True, False, or Uncertain? Explain your answers clearly and succinctly in each case for credit. (No credit will be awarded for statements of True, False, or Uncertain without accompanying explanation.) (a) R' can never go down when you add another variable to the model because adding another variable to the model cannot decrease the residual sum of squares. (b) Other things equal, we can obtain more precise estimates 2 and B3, if Xz and X3, are not highly correlated. (c) We cannot obtain unbiased estimates of B2 and B3 when we have high multicollinearity between Xz and X3 because we have so little variation in X2 holding constant X3 and vice versa