Determine the set of zzz satisfying arg(z−1z+1)=π2\text{arg}(\frac{z-1}{z+1}) = \frac{\pi}{2}arg(z+1z−1)=2π.
A circle with center at iii
An arc of a circle passing through 111 and −1-1−1
The line segment between −1-1−1 and 111
A circle centered at the origin