Answer:
A
Step-by-step explanation:
The linear model can be assessed by the checking the independent variables having power 1 which shows the linear relationship between x and y. For example, as in the option B, C and D, the power of Xi's is one. Whereas the non linear model has the power for independent variables greater than 1. For example, as in option A the model is a quadratic model because X associated with β2 has a power of a 2.
Thus the nonlinear model can be expressed as
Y = β0 + β1X + (β2X)2 + ε.