The locus of the point $z=x+iy$ satisfying the equation $\bigg|\large\frac{z-i}{z+i} \bigg|$$=1$is given by :

Question

\[\begin {array} {1 1} (a)\;x=0 & \quad (b)\;y=0 \\ (c)\;x=y & \quad (d)\;x+y=0 \end {array}\]