If the area bounded by the corve $y=x^{2}+1, y=x$ and the pair of lines $x^{2}+y^{2}+2 x y-4 x-4 y+3=0$ is $K$ units, then the area of the region bounded by the curve $y=x^{2}+1, y=\sqrt{x-1}$ and the pair of lines $(x+y-1)(x+y-3)=0$, is
(a) $K$
(b) $2 \mathrm{~K}$
(c) $\frac{K}{2}$
(d) None of these