A cubical block of wood of edge a and density `rho` floats in water of density `2rho`. The lower surface of the cube just touches the free end of a mass less spring of force constant K fixed at the bottom of the vessel. The weight W put over the block so that it is completely immersed in water without wetting the weight is
A. `a (a^(2) rho g + k)`
B. `a (a rho g + 2k)`
C. `a ((a rho g)/(2) + 2k)`
D. `a (a^(2) rho + (k)/(2))`
