A parabola has a focus of F (8.5,-4) and a directrix of x=9.5.
What is the equation of the parabola?

A) 1/2 y² + 4y - 1= x
B) -1/2y²- 4y +1 = x
C) 1/2y²- 4y+1=x
D) -1/2y² + 4y-1=x