If for any complex number $z$, $|z-1|=1$, then $\large\frac{z-2}{z}=?$

Question

$\begin{array}{1 1}(A)\tan (arg \;z) \\ (B) \cot (arg\; z) \\ (C) i \tan (arg\;z) \\(D) i \cot (arg \;z) \end{array}$