Two identical cylindrical vessel with their bases at the same level each contain a liquid of density `rho`. The height of the liquid in one vessel is `h_(1)` and in the other is `h_(2)` the area of either base is A. What is the work done by gravity is equalising the levels when the two vessels are connected?
A. `2 rho Ag(h_(2)-h_(1))^(2)`
B. `rho Ag(h_(2)-h_(1))^(2)`
C. `(1)/(2) rho Ag(h_(2)-h_(1))^(2)`
D. `(1)/(4) rhoAg(h_(2)-h_(1))^(2)`