Evaluate \int \frac{1}{1− \sin ^{4}⁡x}dx.

Correct Answer is : 12[tan⁡x+1√2tan−1⁡(√2tan⁡x)]+C

\tan ⁡x + {1}/{\sqrt{2}}\tan ^{−1}⁡ (\sqrt{2}\tan ⁡x) + C

\frac{1}{2} [\tan ⁡x− {1}/{\sqrt{2}}\tan ^{−1}⁡ (\sqrt{2}\tan ⁡x) ] + C