In a triangle $ABC$ if $a=4,b=8$ and $\angle B=60^{\circ}$ then $\angle B=?$

Question

$\begin{array}{1 1} \angle B =80^{\circ} \\ \angle B= 90^{\circ} \\ \angle B =60^{\circ} \\ \angle B= 50^{\circ} \end{array} $