Coordinate water molecules of a Cd (II) complex can be successively replaced by $\mathrm{Br}^{-}$finally to result in $\left[\mathrm{CdBr}_{4}\right]^{2-}$ . In this process, the fourth equilibirum constant is observed to be higher than the third one, because
(a)equilibrium constant for the last step is always the highest.
(b)three molecules of $\mathrm{H}_{2} \mathrm{O}$ are released during the fourth step.