The correct answer is option 3: Osmosis. In the process of dialysis, osmosis is the phenomenon involved. Dialysis is a medical procedure used on patients with affected kidneys to remove waste products and excess fluid from the blood. It works by creating a concentration gradient across a semi-permeable membrane, typically a dialyzer or filter. The solute particles, such as waste products and toxins, diffuse from an area of higher concentration (the patient`s blood) to an area of lower concentration (the dialysate solution). Osmosis, on the other hand, is the movement of water molecules across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration. In dialysis, osmosis helps to remove excess fluid from the patient`s blood, as water molecules move from the blood to the dialysate solution.