$\int \frac{\left(\sec ^{-1} x\right)^{5}}{x \sqrt{x^{2}-1}} d x=$ কত ?

$\frac{1}{5}\left(\sec ^{-1} x\right)^{5}+c$

$\frac{1}{6}\left(\sec ^{-1} x\right)^{6}+c$

$\frac{1}{4}\left(\sec ^{-1} x\right)^{4}+c$

$\left(\sec ^{-1} x\right)^{6}+c$