\( \tan \left( 2\tan^{-1}\dfrac{1}{5}+\sec^{-1}\dfrac{\sqrt{5}}{2}+2\tan^{-1}\dfrac{1}{8} \right) \) is equal to:
\( 1 \)
\( 2 \)
\( \dfrac{1}{4} \)
\( \dfrac{5}{4} \)