A) List and briefly explain the assumptions under which the Ordinary Least Squares (OLS) estimator is Best Linear Unbiased Estimator (i.e. the Gauss-Markov Theorem assumptions). [35 marks] B) Define omitted variable bias? When is this bias non-zero? Which of the OLS assumptions is violated? [ 35 marks] C) Suppose you have estimated a model and obtained the following results (robust standard errors in brackets, sample size is 500 observations): Pi=0.33912.894X1i+1.397X2i(0.068)(3.177)(0.229)R2=0.752 C1) Conduct individual significance tests on each of the coefficients at the 95% confidence level and state if they are significantly different from zero. Your answer should include an explanation of how you reached that conclusion. [ 10 marks] C2) Construct 95% confidence intervals for each of the coefficients. [10 marks] C3) You think of another variable X3 that impacts Y. You re-estimate the model and obtain the following results