Let $z=x+i y, w=u+$ iv where $x, y, u, v$ are real. If $w=\frac{2}{z}$ and $z$ moves along the circle $|z-2 i|=2 .$ Then the locus
of $w .$
(a) perpendicular bisector of the line joining $(0,-1)$ and $(0,0)$
(b) circle with centre $(0,0)$ radius 1
(c) circle with centre $(0,0)$ radius 2
(d) straight line passing through $(0,2)$