Three different liquids are filled in a U-tube as shown in figure. Their densities are `rho_(1), rho_(2)` and `rho_(3)` respectively. From the figure we may conclude that
A. `rho_(2) gt rho_(1)`
B. `rho_(1) gt rho_(2)`
C. `rho_(3)=2 (rho_(2)-rho_(1))`
D. `rho_(3)=(rho_(2)+rho_(1))/(2)`