what is the factored form of 9x^6+ 15x^4 + 12x^2
A. 2²(9x4 + 15x2 + 12)
B. 3x(3x5 + 5x3 + 4x)
c. 3x²(3x4 + 5x2 + 4)
D. 3x2(9x6 + 15x1 + 12x²)