If \( y=\dfrac{1}{2}(\sin^{-1}x)^{2} \) , then find \( (1-x^{2})y_{2}-xy_{1} \) . ; Where \( y_{1} \) and \( y_{2} \) denote first and second derivatives of \( y \) respectively.

A \( -1 \)

B \( 0 \)

C \( 1 \)