Find the principal values of the following: $sec^{-1} \bigg( \frac {2} {\sqrt 3} \bigg) $

Question

$\begin{array}{1 1} \frac{-\pi}{6} \\ \frac{-\pi}{\sqrt 3} \\ \frac{-\pi}{3} \\ \frac{\pi}{3} \end{array} $