A U-tube contains water and methylated spirit separated by mercury.The mercury columns in the two arms are in level with 10cm of water in one arm & 12.5cm of spirit in the other.What is specific gravity of spirit ?

Question

$\begin{array}{1 1}(A)\;0.7\\(B)\;0.8\\(C)\;1\\(D)\;1.2\end{array} $