For the Given Function $g(x)$ , Find a Function $f(x)$ Such That $(f \circ g)(x)=x$

Multiple Choice

For the given function $g(x)$ , find a function $f(x)$ such that $(f \circ g) (x) =x$ .
- $g(x) =-18 x$

A) $f(x) =18 x$

B) $f(x) =-\frac{x}{18}$

C) $f(x) =-\frac{x}{18}$ .

D) $f(x) =-\frac{18}{x}$