If $f(x)=4 x-2$, what is the $y$-intercept of $f^{-1}(x)$ ?
A$-2$
B$-\frac{1}{2}$
C$\frac{1}{2}$
D$\frac{1}{4}$
A$-2$
B$-\frac{1}{2}$
C$\frac{1}{2}$
D$\frac{1}{4}$