Consider the polynomial regression model of degree Yi = β0 + β1Xi + β2 + ...+ βr + ui. According to the null hypothesis that the regression is linear and the alternative that is a polynomial of degree r corresponds to: A) H0: βr = 0 vs. βr ≠ 0. B) H0: βr = 0 vs. β1 ≠ 0. C) H0: β3 = 0, ..., βr = 0, vs. H1: all βj ≠ 0, j = 3, ..., r. D) H0: β2 = 0, β3 = 0 ..., βr = 0, vs. H1: at least one βj ≠ 0, j = 2, ..., r.