Answer: Water
Step-by-step explanation:
Though Cell membranes are selectively permeable to solute, cell membranes are permeable to water.
An osmotic pressure is exerted on cells when the osmolarity of their external environmental is more greater than their internal environmental.
When an osmotic pressure is exerted on cells for the cells to survive, water molecules move from the region of lower concentration to a region of higher concentration until there’s a balance in osmolarity.
Cell membranes are freely permeable to water.
Answer is water.