A 3cm cube has its upper face displaced by 0.1cm by a tangential force.If modulus of rigidity of material is $5\times 10^4N/m^2$.Find the force

Question

$\begin{array}{1 1}(A)\;3N\\(B)\;7.5N\\(C)\;4.5N\\(D)\;1.5N\end{array}$