If $y=\tan^{-1}x$, find $\large {\frac{d^2y}{dx^2}}$ in terms of y alone.

Question

$\begin{array}{1 1}(A)\;-2\sin y.\cos^3y\\(B)\;4\sin y.\cos^3y\\(C)\;2\sin y.-\cos^3y\\(D)\;2\sin y.\cos^3y\end{array}$