Suppose we are trying to model Y as a polynomial of X . Which of the following is NOT a valid reason to pick a fourth-order polynomial over a

Suppose we are trying to model Y as a polynomial of X. Which of the following is NOT a valid reason to pick a fourth-order polynomial over a third-order polynomial?

A The adjusted-R2 is higher in the fourth-order polynomial model.

B We believe a model with a fourth-order polynomial in X captures the theoretical relationship between Y and X.

C The coefficient on X4 is statistically significant.

D The R2 is higher in the fourth-order polynomial model.