Choose the correct answer. If $\sin^{-1}(1-x) -2 \sin^{-1} x=\large\frac {\pi}{2},$ then $x$ is equal to

Question

$$(A) \quad 0, \frac {1}{2} \qquad (B) \quad 1, \frac {1} {2} \qquad (C) \quad 0 \qquad (D) \quad \frac {1}{2}$$