Find All Values That Make the Rational Expression Undefined $$\frac { 4 } { r - 4 }$$

Multiple Choice

Find all values that make the rational expression undefined. If the rational expression is defined for all real numbers, so
state.
- $$\frac { 4 } { r - 4 }$$

A) $\mathrm { r } = 4$
B) $r = 0$
C) $r = - 4$
D) Defined for all real numbers