The line $\arg z=\frac{\pi}{4}$ is mapped onto
(a) line passing through $(5,0)$ with slope 1
(b) line passing through $(5,0)$ with slope $-1$
(c) segment of the line passing through $(5,0)$ with slope $-1$ above the U-axis of the $\mathrm{W}$ plane
(d) segment of the line passing through $(5,0)$ with slope $-1$ below the u-axis.