Find the value of the following:<br> $tan^{-1} \bigg(tan \frac{7\pi}{6}\bigg)$

Question

$\begin{array}{1 1} \frac{\pi}{6} \\ \frac{7 \pi}{6} \\ \frac{-7 \pi}{6} \\ \frac{-\pi}{6} \end{array}$