Solve the Problem $f ( x ) = \frac { x } { x - 4 }$

Multiple Choice

Solve the problem.
-Let $f ( x ) = \frac { x } { x - 4 }$ . Find a function $y = g ( x )$ so that $( f \circ g ) ( x ) = x$ .

A) $g ( x ) = x ( x - 4 )$
B) $g ( x ) = \frac { 1 } { x - 4 }$
C) $g ( x ) = \frac { x - 4 } { 4 }$
D) $g ( x ) = \frac { 4 x } { x - 1 }$