Region A has a low solute concentration. Region B has a high solute concentration. They are separated by a selectively permeable membrane that is impermeable to the solute but allows the passage of water. What would make this true?

Answer: osmosis

Explanation: osmosis is the movement of the water molecules from a region of high concentration of solute to a region of low concentration of solute, through a semi-permeable membrane.

This movement occurs until the concentration on both sides is on equilibrium.

Semi permeable membrane allows the movement of water only but not the solute.

In this case, water moves from region A to region B.