$\int \frac{1}{5-x^{2}} d x=?$

$\frac{1}{10} \ln \left|\frac{x-\sqrt{5}}{x+\sqrt{5}}\right|+c$

$\frac{1}{10} \ln \left|\frac{\sqrt{5}+x}{\sqrt{5}-x}\right|+c$

$\frac{1}{2 \sqrt{5}} \ln \left|\frac{x-\sqrt{5}}{x+\sqrt{5}}\right|+c$

$\frac{1}{2 \sqrt{5}} \ln \left|\frac{\sqrt{5}+x}{\sqrt{5}-x}\right|+c$