1) (1 mark) In the interaction model y = Bo+ B1x1+ B 2x2 + B3X1X2+ E, we would first test the significance of_ 2) (2 marks) Which of the following statements are true? A) Autocorrelation arises when there is a perfect linear association between the dependent and independent variables. < B) Autocorrelation implies the error term have differing variances. < C) Autocorrelation causes the estimated regression standard error to be biased. D) Autocorrelation can be tested using the F-statistic. < 3) (12 marks) Describe in details how to perform a two-step weighted least squares estimation dealing with heteroscedasticity. In your discussion, please write down the first-step regression model and the second-step regression model.