AHSME 1983 Problem 25

If $60^a=3$ and $60^b=5$, then $12^{(1-a-b)/\left(2\left(1-b\right)\right)}$ is $\textbf{(A)}\ \sqrt{3} \textbf{(B)}\ 2 \textbf{(C)}\ \sqrt{5} \textbf{(D)}\ 3 \textbf{(E)}\ 2\sqrt{3}$