If in any $\Delta ABC$ $A=30^{\large \circ}$ and $B=60^{\large\circ}$ then find $a: b:c$

Question

$\begin {array} {1 1}(a)\;1 : 2 : 3&(b)\;2 : \sqrt 3: 5\\(c)\;1 : \sqrt 3 :2&(d)\;None \;of\;these\end{array}$