$y=\ln (1+x)$ হলে, $\frac{d^{2} y}{d x^{2}}$$=?$

$\frac{1}{1+x^{2}}$

$\frac{1}{1+x^{2}}$

$\frac{-1}{(1+x)^{2}}$

$-(1+x)^{2}$