Question

The solution that exerts highest osmotic pressure is...

Answer 1

Hint: The osmotic pressure of a solution is the minimum pressure needed to avoid the inward flow of its pure solvent through a semipermeable membrane. It is also known as the measure of a solution's proclivity to absorb a pure solvent through osmosis.

Complete answer:
Osmosis is the net movement of solvent molecules across a selectively permeable membrane into an area of higher solute concentration, in a direction that appears to equalise the solute concentrations on both sides.
Osmotic pressure is the minimum pressure that must be added to a solution to prevent solvent molecules from moving through a semipermeable membrane. It is a colligative property that is influenced by the concentration of solute particles in the solution.
Colligative properties of solutions are those that are affected by the concentration of solute molecules or ions but not by the solute's identity. Colligative properties include reduced vapour pressure, increased boiling point, decreased freezing point, and increased osmotic pressure.
Since osmotic pressure is proportional to the concentration of solute particles, it is a colligative property. The solution with the highest osmotic pressure contains the most colligative ions.

Note:
Osmotic pressure is a colligative property, which means that it is affected by the molar concentration of the solute but not by its identity. Since biological membranes are semipermeable, osmosis is a critical process in biological systems.