The complex numbers $\sin x+i\cos 2x$ and $\cos x-i\sin 2x$ are conjugate for

Question

$\begin{array}{1 1}(A) x=0 \\ (B)x=\large\frac{n \pi}{2} +\frac{\pi}{2} n \in I \\ (C) x= n \pi n \in I \\(D) No\;value\;of\;x \end{array}$