Which one of the following options contains two solutions of the differential equation $\dfrac{\mathrm{d} y}{\mathrm{d} x}=\left ( y-1 \right )x?$
- $\ln\mid y-1 \mid=0.5x^{2}+C$ and $y=1$
- $\ln\mid y-1 \mid=2x^{2}+C$ and $y=1$
- $\ln\mid y-1 \mid=0.5x^{2}+C$ and $y=-1$
- $\ln\mid y-1 \mid=2x^{2}+C$ and $y=-1$