Graph the data in the table. Which kind of function best models the data? Write an equation to model the data.

x y
0 -6
1 -9
2 -12
3 -15
4 -18

A. quadratic; y = -x^2 - 2x
B. exponential; y = -6 • 1.5x
C. linear; y = -3x - 6
D. quadratic; y = -x^2 + 2x - 6