The answer is c. edema.
Edema is a condition in which there is too much water in spaces surrounding cells. It results when blood vessels are leaky, so a fluid from blood vessels enters the nearby tissue. This extra fluid accumulates and, thus, tissue swells.
Ion is an atom or a molecule with a net charge, either positive (cation) or negative (anion). Osmosis is the movement of solvent molecules from a higher solute concentration to a lower solute concentration.