A complex number $z$ is said to be unimodular if $| z | = 1$. Let $z _ { 1 }$ and $z _ { 2 }$ are complex numbers such that $\frac { z _ { 1 } - 2 z _ { 2 } } { 2 - z _ { 1 } \bar { z } _ { 2 } }$ is unimodular and $z _ { 2 }$ is not unimodular, then the point $z _ { 1 }$ lies on a\\
(1) circle of radius $\sqrt { 2 }$\\
(2) straight line parallel to $x$-axis\\
(3) straight line parallel to $y$-axis\\
(4) circle of radius 2