Victoria was given the expression 5x - 4x^2 - 1 + x - 8x^2 + 7 and asked to simplify it. How can she simplify the expression?

A. -12x^2 + 6x + 6

B. 13x^2 - 5x + 6

C. -4x^2 + 6x + 8

D. 4x^2 + 4x + 8