For which rational expression is -2 an excluded value of $x$?
A$\frac{x-3}{x^2-4}$
B$\frac{x-3}{x^2+4}$
C$\frac{x^2-4}{x-3}$
D$\frac{x^2+4}{x-3}$
A$\frac{x-3}{x^2-4}$
B$\frac{x-3}{x^2+4}$
C$\frac{x^2-4}{x-3}$
D$\frac{x^2+4}{x-3}$