If f(x) = -x^2 + 6x - 1 and g(x) = 3x^2 - 4x-1, find (f - g)(x).

A. (f- g)(x) = -4x^2 - 2x
B. (f- g)(x) = 2x^2 + 2x-2
C. (f- g)(x) = 4x^2 - 10x
D. (f - g)(x) = -4x^2 + 10x