Final answer:
In an isotonic solution, cells will remain the same size as the osmotic pressure inside and outside the cell is balanced. The correct option is c.
Step-by-step explanation:
Cells placed in an isotonic solution will remain the same size because the amount of water entering the cell is the same as the amount leaving the cell. In an isotonic solution, the osmotic pressure inside and outside the cell is balanced, so there is no net movement of water into or out of the cell.
Therefore, the correct option is c.