Answer:
Semi-permeable membrane.
Step-by-step explanation:
Solutions on both sides of a semipermeable membrane are equal to the concentration of automatic movement by the movement of solutions and/or water across the membrane.
Importantly, when cells have an equal concentration of solutes inside and outside the cell, they receive the name of "isotonic". In these cells, the osmotic pressure on both sides of the semipermeable membrane is equal.