Simplify the rational expression: $\frac{x^2-2x-8}{2x^2-8}$

$\frac{x-4}{2x-4}$

$\frac{x+2}{2x-4}$

$\frac{x}{2}-1$

$\frac{x-4}{2x+4}$

$\frac{1}{2}-4x$

$\frac{2x-4}{x-4}$