The value of the integral $\int_{1}^{2}\left(\frac{t^{4} + 1}{t^{6} + 1}\right) dt$ is:
\( \tan^{-1}\left(\dfrac{1}{2}\right)+\dfrac{1}{3}\tan^{-1}\!8-\dfrac{\pi}{3} \)
\( \tan^{-1}\!2-\dfrac{1}{3}\tan^{-1}\!8+\dfrac{\pi}{3} \)
\( \tan^{-1}\!2+\dfrac{1}{3}\tan^{-1}\!8-\dfrac{\pi}{3} \)
\( \tan^{-1}\dfrac{1}{2}-\dfrac{1}{3}\tan^{-1}\!8+\dfrac{\pi}{3} \)