Let $\mathrm{z}=\mathrm{x}+\mathrm{iy}, \mathrm{w}=\mathrm{u}+\mathrm{iv}$ where $\mathrm{x}, \mathrm{y}, \mathrm{u}, \mathrm{v}$ are real. If $\mathrm{w}=2 \mathrm{iz}$ and $\mathrm{z}$ moves such that $\arg \mathrm{z}=\frac{\pi}{4}$, the locus of $\mathrm{w}$ is
(a) Straight line
(b) circle
(c) ellipse
(d) parabola