The sides of a $\Delta$le are respectively 7cm,$4\sqrt 3$cm and $\sqrt{13}$cm then the smallest angle of the triangle is

Question

$\begin{array}{1 1}(a)\;\large\frac{\pi}{6}&(b)\;\large\frac{\pi}{3}\\(c)\;\large\frac{\pi}{4}&(d)\;\large\frac{\pi}{5}\end{array}$