Find the Specified Domain and Express It in Interval Notation $f ( x ) = \sqrt { x - 4 }$

Multiple Choice

Find the specified domain and express it in interval notation.
-For $f ( x ) = \sqrt { x - 4 }$ and $g ( x ) = \frac { 1 } { x - 6 }$ , what is the domain of $g / f$ ?

A) $( 4,6 ) \cup ( 6 , \infty )$
B) $( 4 , \infty )$
C) $[ 4,6 ) \cup ( 6 , \infty )$
D) $[ 4 , \infty )$