# If $\;x\sqrt{1+y}+y\sqrt{1+x}=0, \;$ Evaluate $\large\frac{dy}{dx}$
$\begin{array}{1 1} (A) \large \frac{-1}{1+x^2}\\ (B) \large \frac{1}{1+x^2}\\ (C) \large \frac{x-1}{1+x^2} \\ (D) \large \frac{1-x}{1+x^2} \end{array}$