The slope f'(x) at each point (x, y) on a curve y = f(x) is given along with a particular point (a, b) on the curve. Use this information to find f(x). f'(x)=3x^2+6x-2; (0,6) A: x^3 + 3x^2 - 2x B: x^3 + 3x^2 - 2x + 6 C: x^3 + 3x^2 - 2x + c D: x^3 + 3x^2 - 2x + 6 + c