The correct option is B on the real axis
|ω|=1⇒∣∣∣1−izz−i∣∣∣=1⇒|1−iz|=|z−i|⇒|−i(z+i)|=|z−i|⇒|z+i|=|z−i|
Therefore, z lies on the perpendicular bisector of line segment joining (0,−1) and (0,1).
Hence, the locus of z is y=0, so z lies on the real axis.