Simplify and state excluded values: $\frac{x^2-5x+6}{x^2-4}$

• A. $\frac{x-3}{x+2}$, $x\ne -2$
• B. $\frac{x-3}{x+2}$, for all $x$
• C. $x-3$, $x\ne -2$
• D. $\frac{x-3}{x+2}$ , $x\ne 2$ and $x\ne -2$