Which of the following expressions is equivalent to − 4 x 3 − 12 x 3 + 9 x 2 ? ​ A. x 8 B. − 7 x 8 C. − 8 x 3 + 9 x 2 D. − 16 x 3 + 9 x 2 E. − 16 x 6 + 9 x 2