Determine the Domain of the Function $f ( x ) = \frac { 2 x } { x - 9 }$

Multiple Choice

Determine the domain of the function.
- $f ( x ) = \frac { 2 x } { x - 9 }$

A) $\{ x \mid x \neq - 9 \}$
B) $\{ x \mid x \neq 0 \}$
C) $\{ x \mid x \text { is a real number } \}$
D) $\{ x \mid x \neq 9 \}$