Concept:A saturated solution is a dynamic balance where the rate of dissolution equals the rate of crystallisation.
Explanation:In a saturated solution at a given temperature, the undissolved solute remains in equilibrium with the solute particles that have already dissolved.
The rate at which solute particles go into solution is exactly equal to the rate at which dissolved particles return to the undissolved state.
Because these two rates are equal, the concentration of the solution remains constant.
This equilibrium is specifically between undissolved solute and dissolved solute particles, not with the solvent or with insoluble particles.
Answer:B. dissolved solute particles