Which Equation Represents a Complete Second-Order Model for Two Quantitative

Multiple Choice

Which equation represents a complete second-order model for two quantitative independent variables?

A) $E ( y ) = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } ^ { 2 } + \beta _ { 2 } x _ { 2 } ^ { 2 } + \beta _ { 3 } x _ { 1 } ^ { 2 } x _ { 2 } + \beta _ { 4 } x _ { 1 } x _ { 2 } ^ { 2 } + \beta _ { 5 } x _ { 1 } ^ { 2 } x _ { 2 } ^ { 2 }$
B) $E ( y ) = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } + \beta _ { 2 } x _ { 2 } + \beta _ { 3 } x _ { 1 } x _ { 2 } + \beta _ { 4 } x _ { 1 } ^ { 2 } + \beta _ { 5 } x _ { 2 } ^ { 2 }$
C) $E ( y ) = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } + \beta _ { 2 } x _ { 2 } + \beta _ { 3 } x _ { 1 } ^ { 2 } + \beta _ { 4 } x _ { 2 } ^ { 2 }$
D) $E ( y ) = \beta _ { 0 } + \beta _ { 1 } x _ { 1 } x _ { 2 } + \beta _ { 2 } x _ { 1 } ^ { 2 } + \beta _ { 3 } x _ { 2 } ^ { 2 }$