$\int \frac{1}{\sqrt{18-2 x^{2}}} d x=$ কত ?

$\frac{1}{\sqrt{2}} \sin ^{-1} \frac{x}{3}+c$

$\frac{1}{3 \sqrt{2}} \tan ^{-1} \frac{x}{3}+c$

$\frac{1}{6 \sqrt{2}} \ln \left|\frac{3+x}{3-x}\right|+c$

$\frac{1}{6 \sqrt{2}} \ln \left|\frac{x-3}{x+3}\right|+c$