Let `T_(1)` be surface tension between solid and air, `T_(2)` be the surface tension between solid and liquid and T be the surface tension between liquid and air. Then in equilibrium, for a drop of liquid on a clean glass plate, the correct relation is (`theta` is angle of contact)

Options

A. `costheta=T/(T_(1)+T_(2))`
B. `costheta=T/(T_(1)-T_(2))`
C. `costheta=(T_(1)+T_(2))/T`
D. `costheta=(T_(1)-T_(2))/T`