$\begin{array}{1 1}(a)\;\text{It is the equilibrium hydrostatic pressure from solution to the solvent side when the two are separated by a semipermeable membrane }\\(b)\;\text{It is the excess pressure which should be applied to the solution in order to make its vapour pressure equal to that of the solvent}\\(c)\;\text{It is the additional pressure that must be applied to the solvent to prevent its flow in to the solution through a semipermeable membrane}\\(d)\;\text{Both (a) and (b)}\end{array}$
