A possible value of \( \tan\!\left(\frac{1}{4}\sin^{-1}\!\frac{\sqrt{63}}{8}\right) \) is:
\( \sqrt{7} - 1 \)
\( 2\sqrt{2} - 1 \)
\( \frac{1}{\sqrt{7}} \)
\( \frac{1}{2\sqrt{2}} \)