Tell Whether a Linear Model or a Quadratic Model Is $x ^ { 2 }$

Multiple Choice

Tell whether a linear model or a quadratic model is appropriate for the data. If linear, tell whether the slope should be
positive or negative. If quadratic, decide whether the leading coefficient a of $x ^ { 2 }$ should be positive or negative.
-The amount of sales tax paid as a function of the sales price.

A) quadratic; positive
B) linear; negative
C) quadratic; negative
D) linear; positive