If $|\overrightarrow a|=3,\:|\overrightarrow b|=\large\frac{\sqrt 2}{3}$, then $\overrightarrow a\times\overrightarrow b$ is a unit vector if the angle between $\overrightarrow a$ and $\overrightarrow b$ is ?

Question

$\begin{array}{1 1} \large\frac{\pi}{6} \\ \large\frac{\pi}{4} \\ \large\frac{\pi}{3} \\ \large\frac{\pi}{2} \end{array} $