What Inputs Are Defined for the Expression $$\frac { x } { 9 x + 4 }$$

Multiple Choice

What inputs are defined for the expression? $$\frac { x } { 9 x + 4 }$$

A) $R , x \neq - \frac { 9 } { 4 }$
B) $R , x \neq \frac { 4 } { 9 }$
C) $R , x \neq - \frac { 4 } { 9 }$
D) $R, x \neq \frac { 9 } { 4 }$
E) $R , x \neq 0$