In the XY plane above , O is the center of the circle. The measure of $\angle AOX$ is

Question

$\begin{array}{1 1} (a)\;\frac{\pi}{6} \\ (b)\; 5 \frac{\pi}{6} \\ (c)\; \frac{\pi}{3} \\ (d)\; \frac{2 \pi}{6} \end{array}$