they produce asymptotically valid inferences even if you do not know the form of the conditional variance function. it makes the OLS estimator BLUE,...

B. they produce asymptotically valid inferences even if you do not know the form of the conditional variance function. C. it makes the OLS estimator BLUE, even in the presence of heteroskedasticity. D. they do not unnecessarily complicate matters, since in real-world applications, the functional form of the conditional variance can easily be found. (15 points) What does the Gauss-Markov theorem prove? What are the assumptions required for the Gauss-Markov theorem? What is its importance?