Question #N37

The function $f(x)$ is defined as $f(x) = \frac{x^2 - 9}{x - 3}$. For what value(s) of $x$ is $f(x)$ undefined?
A. x = 3 only
B. x = -3 only
C. x = 3 and x = -3
D. x = 0 only