Four cuboids with the same lengths, breadths and heights are placed in water. The cuboids are kept at an equal depth and in the same orientations by vertical rods, as illustrated. Water has density $\rho$. Cuboid W is made from a material of density $4\rho$. Cuboid X is made from a material of density $2\rho$. Cuboid Y is made from a material of density $\rho$. Cuboid Z is made from a material of density $0.5\rho$. Which statement is correct?
- AThe upthrust of the water on each of the cuboids is the same.
- BThe upthrust of the water on W is twice the upthrust of the water on X.
- CThe upthrust of the water on X is twice the upthrust of the water on W.
- DThe upthrust of the water on Y is zero.