Answer: W
Step-by-step explanation:
The cell in liquid W will look the smallest out of the four because of Osmosis.
Osmosis is a process by which water molecules move from an area of relatively higher concentration of water to an area with a relatively lower concentration through a selectively permeable membrane(cell membrane).
With W being saltier than the cell, water molecules will move from the cell to liquid W to balance the concentrations inside and outside the cell which will lead to the cell in W being smaller.