Answer: The correct answer for the fill in the blank is osmosis.
Osmosis is defined as the movement of solvent (like water) from a region where the concentration of solute is lower to a region where the concentration of solute is higher though a semipermeable membrane.
In other words, it is the water movement from an area where its ( water ) concentration is higher to an area where its concentration is lower.
This process does not require any energy as water is moving along the concentration gradient.
