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. `(h_(1)-h_(2))grho`
B. `(h_(1)h_(2))gArho`
C. `(1)/(2)(h_(1)-h_(2))^(2)gArho`
D. `(1)/(4)(h_(1)-h_(2))^(2)gArho`
