Use the grouping method to factor the polynomial completely.

9x^9-24x^5-12x^4

A. 3x^4(3x^5-8x^2-4x)
B. 3x^4(3x^5-8x-4)
C. 3x^9(3x^5-8x-4)
D. 3x^9(3x^5-8x^2-4x)