What is the difference of the following polynomials?

(6x^3-2x^2+4) - (2x^3+4x^2-5)


A. 4x^3-2x^2-1
B. 8x^3+6x^2-1
C. 4x^3-2x^2+1
D. 4x^3-6x^2+9