Find All Numbers for Which the Rational Expression Is Not $\frac{x^{2}-81}{x^{2}-2 x-15}$

Multiple Choice

Find all numbers for which the rational expression is not defined.
- $\frac{x^{2}-81}{x^{2}-2 x-15}$

A) $x=9$ and $x=-9$
B) $x=0$
C) $x=5$ and $x=-3$
D) $x=-5$ and $x=3$